pageinspect源码解读
pageinspect提供从低层次检查数据库页内容的函数，可用于debug，所有的函数只允许superusers使用。
其源码在openGauss源码contrib/pageinspect目录下。
[gs@sgnode ~]$ cd /data/openGauss-server/contrib/pageinspect
[gs@sgnode pageinspect]$ ll
total 76
-rw-rw-r--. 1 gs gs 15099 Jun 22 13:23 btreefuncs.cpp
-rw-rw-r--. 1 gs gs 1637 Jun 22 13:24 fsmfuncs.cpp
-rw-rw-r--. 1 gs gs 9185 Jun 22 13:13 ginfuncs.cpp
-rwxrwxr-x. 1 gs gs 6743 Jun 22 13:23 heapfuncs.cpp
-rw-rw-r--. 1 gs gs 458 Jun 22 13:13 Makefile
-rw-rw-r--. 1 gs gs 3581 Jun 22 13:13 pageinspect--1.0.sql
-rw-rw-r--. 1 gs gs 173 Jun 22 13:13 pageinspect.control
-rw-rw-r--. 1 gs gs 1255 Jun 22 13:13 pageinspect--unpackaged--1.0.sql
-rw-rw-r--. 1 gs gs 17263 Jun 22 13:23 rawpage.cpp
pageinspect编译
在源码目录直接编译，编译后的相关文件在$GAUSSHOME目录下相应路径
[gs@sgnode pageinspect]$ make
g++ -std=c++11 -D_GLIBCXX_USE_CXX11_ABI=0 -fsigned-char -DSTREAMPLAN -DPGXC -mcx16 -msse4.2 -O0 -Wall -Wpointer-arith -Wno-write-strings -fnon-call-exceptions -fno-common -freg-struct-return -pipe -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -DENABLE_GSTRACE -fno-aggressive-loop-optimizations -Wno-attributes -fno-omit-frame-pointer -fno-expensive-optimizations -Wno-unused-but-set-variable -fstack-protector -Wl,-z,relro,-z,now -Wl,-z,noexecstack -std=c++14 -pthread -D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS -fpic -I. -I. -I../../src/include -I../../src/lib/gstrace -D_GNU_SOURCE -I/data/openGauss-third_party_binarylibs/dependency/install_tools_centos7.6_x86_64/unixodbc/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libobs/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcgroup/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/openssl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/liborc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libparquet/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/protobuf/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/grpc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/boost/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/llvm/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/kerberos/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/postgresql-hll/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/cjson/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libedit/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/numactl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/zlib1.2.11/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/lz4/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcurl/comm/include -c -o rawpage.o rawpage.cpp
g++ -std=c++11 -D_GLIBCXX_USE_CXX11_ABI=0 -fsigned-char -DSTREAMPLAN -DPGXC -mcx16 -msse4.2 -O0 -Wall -Wpointer-arith -Wno-write-strings -fnon-call-exceptions -fno-common -freg-struct-return -pipe -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -DENABLE_GSTRACE -fno-aggressive-loop-optimizations -Wno-attributes -fno-omit-frame-pointer -fno-expensive-optimizations -Wno-unused-but-set-variable -fstack-protector -Wl,-z,relro,-z,now -Wl,-z,noexecstack -std=c++14 -pthread -D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS -fpic -I. -I. -I../../src/include -I../../src/lib/gstrace -D_GNU_SOURCE -I/data/openGauss-third_party_binarylibs/dependency/install_tools_centos7.6_x86_64/unixodbc/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libobs/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcgroup/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/openssl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/liborc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libparquet/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/protobuf/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/grpc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/boost/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/llvm/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/kerberos/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/postgresql-hll/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/cjson/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libedit/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/numactl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/zlib1.2.11/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/lz4/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcurl/comm/include -c -o heapfuncs.o heapfuncs.cpp
g++ -std=c++11 -D_GLIBCXX_USE_CXX11_ABI=0 -fsigned-char -DSTREAMPLAN -DPGXC -mcx16 -msse4.2 -O0 -Wall -Wpointer-arith -Wno-write-strings -fnon-call-exceptions -fno-common -freg-struct-return -pipe -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -DENABLE_GSTRACE -fno-aggressive-loop-optimizations -Wno-attributes -fno-omit-frame-pointer -fno-expensive-optimizations -Wno-unused-but-set-variable -fstack-protector -Wl,-z,relro,-z,now -Wl,-z,noexecstack -std=c++14 -pthread -D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS -fpic -I. -I. -I../../src/include -I../../src/lib/gstrace -D_GNU_SOURCE -I/data/openGauss-third_party_binarylibs/dependency/install_tools_centos7.6_x86_64/unixodbc/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libobs/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcgroup/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/openssl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/liborc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libparquet/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/protobuf/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/grpc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/boost/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/llvm/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/kerberos/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/postgresql-hll/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/cjson/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libedit/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/numactl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/zlib1.2.11/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/lz4/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcurl/comm/include -c -o btreefuncs.o btreefuncs.cpp
g++ -std=c++11 -D_GLIBCXX_USE_CXX11_ABI=0 -fsigned-char -DSTREAMPLAN -DPGXC -mcx16 -msse4.2 -O0 -Wall -Wpointer-arith -Wno-write-strings -fnon-call-exceptions -fno-common -freg-struct-return -pipe -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -DENABLE_GSTRACE -fno-aggressive-loop-optimizations -Wno-attributes -fno-omit-frame-pointer -fno-expensive-optimizations -Wno-unused-but-set-variable -fstack-protector -Wl,-z,relro,-z,now -Wl,-z,noexecstack -std=c++14 -pthread -D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS -fpic -I. -I. -I../../src/include -I../../src/lib/gstrace -D_GNU_SOURCE -I/data/openGauss-third_party_binarylibs/dependency/install_tools_centos7.6_x86_64/unixodbc/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libobs/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcgroup/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/openssl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/liborc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libparquet/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/protobuf/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/grpc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/boost/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/llvm/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/kerberos/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/postgresql-hll/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/cjson/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libedit/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/numactl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/zlib1.2.11/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/lz4/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcurl/comm/include -c -o fsmfuncs.o fsmfuncs.cpp
g++ -std=c++11 -D_GLIBCXX_USE_CXX11_ABI=0 -fsigned-char -DSTREAMPLAN -DPGXC -mcx16 -msse4.2 -O0 -Wall -Wpointer-arith -Wno-write-strings -fnon-call-exceptions -fno-common -freg-struct-return -pipe -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -DENABLE_GSTRACE -fno-aggressive-loop-optimizations -Wno-attributes -fno-omit-frame-pointer -fno-expensive-optimizations -Wno-unused-but-set-variable -fstack-protector -Wl,-z,relro,-z,now -Wl,-z,noexecstack -std=c++14 -pthread -D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS -fpic -I. -I. -I../../src/include -I../../src/lib/gstrace -D_GNU_SOURCE -I/data/openGauss-third_party_binarylibs/dependency/install_tools_centos7.6_x86_64/unixodbc/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libobs/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcgroup/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/openssl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/liborc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libparquet/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/protobuf/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/grpc/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/boost/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/llvm/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/kerberos/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/postgresql-hll/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/cjson/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libedit/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/numactl/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/zlib1.2.11/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/lz4/comm/include -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcurl/comm/include -c -o ginfuncs.o ginfuncs.cpp
g++ -std=c++11 -D_GLIBCXX_USE_CXX11_ABI=0 -fsigned-char -DSTREAMPLAN -DPGXC -mcx16 -msse4.2 -O0 -Wall -Wpointer-arith -Wno-write-strings -fnon-call-exceptions -fno-common -freg-struct-return -pipe -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -DENABLE_GSTRACE -fno-aggressive-loop-optimizations -Wno-attributes -fno-omit-frame-pointer -fno-expensive-optimizations -Wno-unused-but-set-variable -fstack-protector -Wl,-z,relro,-z,now -Wl,-z,noexecstack -std=c++14 -pthread -D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS -fpic -shared -o pageinspect.so rawpage.o heapfuncs.o btreefuncs.o fsmfuncs.o ginfuncs.o -L../../src/common/port -pthread -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/zlib1.2.11/comm/lib -I/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/zlib1.2.11/comm/include -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libedit/comm/lib -L/data/openGauss-third_party_binarylibs/platform/centos7.6_x86_64/Huawei_Secure_C/comm/lib -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/openssl/comm/lib -L/data/openGauss-third_party_binarylibs/buildtools/centos7.6_x86_64/libstd/gcc7.3.0/comm/lib -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcgroup/comm/lib -L -L/data/openGauss-third_party_binarylibs/dependency/install_tools_centos7.6_x86_64/unixodbc/lib -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libobs/comm/lib -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/kerberos/comm/lib -L../../src/gstrace//common -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/numactl/comm/lib -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/libcurl/comm/lib -L/data/openGauss-third_party_binarylibs/dependency/centos7.6_x86_64/jemalloc/debug/lib
[gs@sgnode pageinspect]$ make install
/usr/bin/mkdir -p '/data/openGauss-server/dest/lib/postgresql'
/usr/bin/mkdir -p '/data/openGauss-server/dest/share/postgresql/extension'
/usr/bin/mkdir -p '/data/openGauss-server/dest/share/postgresql/extension'
/bin/sh ../../config/install-sh -c -m 755 pageinspect.so '/data/openGauss-server/dest/lib/postgresql/pageinspect.so'
/bin/sh ../../config/install-sh -c -m 644 ./pageinspect.control '/data/openGauss-server/dest/share/postgresql/extension/'
/bin/sh ../../config/install-sh -c -m 644 ./pageinspect--1.0.sql ./pageinspect--unpackaged--1.0.sql '/data/openGauss-server/dest/share/postgresql/extension/'
[gs@sgnode pageinspect]$
在gsql命令行执行create extension后可使用。
cc1=# create extension pageinspect;
CREATE EXTENSION
// 查询pageinspect提供的函数
cc1=# \x
Expanded display is on.
cc1=# \df
List of functions
-[ RECORD 1 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | bt_metap
Result data type | record
Argument data types | relname text, OUT magic integer, OUT version integer, OUT root integer, OUT level integer, OUT fastroot integer, OUT fastlevel integer
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 2 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | bt_page_items
Result data type | SETOF record
Argument data types | relname text, blkno integer, OUT itemoffset smallint, OUT ctid tid, OUT itemlen smallint, OUT nulls boolean, OUT vars boolean, OUT data text
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 3 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | bt_page_stats
Result data type | record
Argument data types | relname text, blkno integer, OUT blkno integer, OUT type "char", OUT live_items integer, OUT dead_items integer, OUT avg_item_size integer, OUT page_size integer
, OUT free_size integer, OUT btpo_prev integer, OUT btpo_next integer, OUT btpo integer, OUT btpo_flags integer
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 4 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | fsm_page_contents
Result data type | text
Argument data types | page bytea
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 5 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | get_raw_page
Result data type | bytea
Argument data types | text, integer
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 6 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | get_raw_page
Result data type | bytea
Argument data types | text, text, integer
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 7 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | gin_leafpage_items
Result data type | SETOF record
Argument data types | page bytea, OUT first_tid tid, OUT nbytes smallint, OUT tids tid[]
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 8 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | gin_metapage_info
Result data type | record
Argument data types | page bytea, OUT pending_head bigint, OUT pending_tail bigint, OUT tail_free_size integer, OUT n_pending_pages bigint, OUT n_pending_tuples bigint, OUT n_total_pa
ges bigint, OUT n_entry_pages bigint, OUT n_data_pages bigint, OUT n_entries bigint, OUT version integer
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 9 ]-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | gin_page_opaque_info
Result data type | record
Argument data types | page bytea, OUT rightlink bigint, OUT maxoff integer, OUT flags text[]
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 10 ]------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | heap_page_items
Result data type | SETOF record
Argument data types | page bytea, OUT lp smallint, OUT lp_off smallint, OUT lp_flags smallint, OUT lp_len smallint, OUT t_xmin xid, OUT t_xmax xid, OUT t_field3 integer, OUT t_ctid ti
d, OUT t_infomask2 integer, OUT t_infomask integer, OUT t_hoff smallint, OUT t_bits text, OUT t_oid oid
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 11 ]------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | page_compress_meta
Result data type | text
Argument data types | relation_name bytea, blkno integer, blknum integer, OUT compress_meta text
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 12 ]------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | page_compress_meta_usage
Result data type | text
Argument data types | OUT help text
Type | normal
fencedmode | f
propackage | f
prokind | f
-[ RECORD 13 ]------+------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
Schema | public
Name | page_header
Result data type | record
Argument data types | page bytea, OUT lsn text, OUT tli smallint, OUT flags smallint, OUT lower smallint, OUT upper smallint, OUT special smallint, OUT pagesize smallint, OUT version
smallint, OUT prune_xid xid
Type | normal
fencedmode | f
propackage | f
prokind | f
pageinspect源码
- 函数 get_raw_page(text, int4) RETURNS bytea
查看页数据，关联rawpage.cpp get_raw_page 方法。
/*
* get_raw_page
*
* Returns a copy of a page from shared buffers as a bytea
* 以bytea的形式从共享缓冲区返回页的副本
*/
PG_FUNCTION_INFO_V1(get_raw_page);
Datum get_raw_page(PG_FUNCTION_ARGS)
{
text* relname = PG_GETARG_TEXT_P(0);
uint32 blkno = PG_GETARG_UINT32(1);
bytea* raw_page = NULL;
/*
* We don't normally bother to check the number of arguments to a C
* function, but here it's needed for safety because early 8.4 beta
* releases mistakenly redefined get_raw_page() as taking three arguments.
* 检查参数个数，8.4 beta之前的版本错误地将get_raw_page()重定义为接受3个参数
*/
if (PG_NARGS() != 2)
ereport(ERROR,
(errmsg("wrong number of arguments to get_raw_page()"),
errhint("Run the updated pageinspect.sql script.")));
// 获取页面数据
raw_page = get_raw_page_internal(relname, MAIN_FORKNUM, blkno);
// 返回页面数据
PG_RETURN_BYTEA_P(raw_page);
}
/*
* relname: 表
* forknum: fork number，main: 0, fsm: 1, vm: 2, init: 4
* blkno: 页的编号
*/
static bytea* get_raw_page_internal(text* relname, ForkNumber forknum, BlockNumber blkno)
{
bytea* raw_page = NULL;
RangeVar* relrv = NULL;
Relation rel;
char* raw_page_data = NULL;
Buffer buf;
// 非超级用户返回错误
if (!superuser())
ereport(
ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use raw functions"))));
// 初始化RangeVar，解析relname转换为RangeVar，relname格式可为：relname, schemaname.relanme, catalogname.schemaname.relname
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
// 打开relation
rel = relation_openrv(relrv, AccessShareLock);
/* Check that this relation has storage */
// 检查relation是否有存储空间
if (rel->rd_rel->relkind == RELKIND_VIEW)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot get raw page from view \"%s\"", RelationGetRelationName(rel))));
if (rel->rd_rel->relkind == RELKIND_CONTQUERY)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot get raw page from contview for streaming engine \"%s\"",
RelationGetRelationName(rel))));
if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot get raw page from composite type \"%s\"", RelationGetRelationName(rel))));
if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot get raw page from foreign table \"%s\"", RelationGetRelationName(rel))));
if (rel->rd_rel->relkind == RELKIND_STREAM)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot get raw page from stream for streaming engine \"%s\"",
RelationGetRelationName(rel))));
/*
* Reject attempts to read non-local temporary relations; we would be
* likely to get wrong data since we have no visibility into the owning
* session's local buffers.
* 非本地临时表不能访问，如果是则抛出异常
*/
if (RELATION_IS_OTHER_TEMP(rel))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions")));
// 判断参数blkno(页编号) >= 页数量，则抛出异常
if (blkno >= RelationGetNumberOfBlocks(rel))
elog(ERROR, "block number %u is out of range for relation \"%s\"", blkno, RelationGetRelationName(rel));
/* Initialize buffer to copy to */
// 初始化raw_page
raw_page = (bytea*)palloc(BLCKSZ + VARHDRSZ);
SET_VARSIZE(raw_page, BLCKSZ + VARHDRSZ);
raw_page_data = VARDATA(raw_page);
/* Take a verbatim copy of the page */
// 将页编号blkno的所有数据读出来
buf = ReadBufferExtended(rel, forknum, blkno, RBM_NORMAL, NULL);
LockBuffer(buf, BUFFER_LOCK_SHARE);
memcpy(raw_page_data, BufferGetPage(buf), BLCKSZ);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buf);
relation_close(rel, AccessShareLock);
return raw_page;
}
- 函数 get_raw_page(text, text, int4) RETURNS bytea
查看页数据，关联rawpage.cpp get_raw_page_fork 方法。与get_raw_page方法类似，增加了指定fork。
/*
* get_raw_page_fork
*
* Same, for any fork
*/
PG_FUNCTION_INFO_V1(get_raw_page_fork);
Datum get_raw_page_fork(PG_FUNCTION_ARGS)
{
text* relname = PG_GETARG_TEXT_P(0);
text* forkname = PG_GETARG_TEXT_P(1);
uint32 blkno = PG_GETARG_UINT32(2);
bytea* raw_page = NULL;
ForkNumber forknum;
// 获取forkname对应的number，main: 0, fsm: 1, vm: 2, init: 4
forknum = forkname_to_number(text_to_cstring(forkname));
// 与get_raw_page调用相同的方法获取页面数据
raw_page = get_raw_page_internal(relname, forknum, blkno);
PG_RETURN_BYTEA_P(raw_page);
}
用gsql执行，查看返回的页面数据，可以看到前面40byte的头部数据，以及5个tuple的行指针，尾部有5个元组，中间是空闲空间未填充。
cc1=# create table m(id int);
CREATE TABLE
cc1=# insert into m select generate_series(1,5);
cc1=# \x
Expanded display is on.
cc1=# select * from get_raw_page('m',0);
-[ RECORD 1 ]+--------------------------------------------------------------------------------------
get_raw_page | \x0000000010fdf602000000003c00601f00200620000000005d380000000000000000000000000000e09f3800c09f3800a09f3800809f3800609f3800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000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cc1=#
- 函数 page_header(IN page bytea,OUT lsn text,OUT tli smallint,OUT flags smallint,OUT lower smallint,OUT upper smallint,OUT special smallint,OUT pagesize smallint,OUT version smallint,OUT prune_xid xid)
查看页头信息，关联rawpage.cpp page_header 方法。
/*
* page_header
*
* Allows inspection of page header fields of a raw page
* 允许检查页面数据的页头
*/
PG_FUNCTION_INFO_V1(page_header);
Datum page_header(PG_FUNCTION_ARGS)
{
// 页面数据
bytea* raw_page = PG_GETARG_BYTEA_P(0);
uint32 raw_page_size;
TupleDesc tupdesc;
Datum result;
HeapTuple tuple;
Datum values[11];
bool nulls[11];
PageHeader page;
XLogRecPtr lsn;
char lsnchar[64];
errno_t rc = EOK;
// 非超级用户报错
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use raw page functions"))));
raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
page = (PageHeader)VARDATA(raw_page);
/*
* Check that enough data was supplied, so that we don't try to access
* fields outside the supplied buffer.
* 页大小<需要获取的页头大小，没有足够的数据，则抛出异常
*/
if (raw_page_size < GetPageHeaderSize(page))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("input page too small (%d bytes)", raw_page_size)));
/* Build a tuple descriptor for our result type */
// 构建一个元组描述符，该函数包含OUT参数，以这些参数类型进行构建
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* Extract information from the page header */
// 从页头提取需要返回的信息
lsn = PageGetLSN(page);
rc = snprintf_s(lsnchar, sizeof(lsnchar), sizeof(lsnchar) - 1, "%X/%X", (uint32)(lsn >> 32), (uint32)lsn);
securec_check_ss(rc, "\0", "\0");
rc = memset_s(nulls, sizeof(nulls), 0, sizeof(nulls));
securec_check_c(rc, "\0", "\0");
values[0] = CStringGetTextDatum(lsnchar);
values[1] = UInt16GetDatum(page->pd_checksum);
values[2] = UInt16GetDatum(page->pd_flags);
values[3] = UInt16GetDatum(page->pd_lower);
values[4] = UInt16GetDatum(page->pd_upper);
values[5] = UInt16GetDatum(page->pd_special);
values[6] = UInt16GetDatum(PageGetPageSize(page));
values[7] = UInt16GetDatum(PageGetPageLayoutVersion(page));
if (PageIs8BXidHeapVersion(page)) {
values[8] = TransactionIdGetDatum(page->pd_prune_xid + ((HeapPageHeader)page)->pd_xid_base);
values[9] = TransactionIdGetDatum(((HeapPageHeader)page)->pd_xid_base);
values[10] = TransactionIdGetDatum(((HeapPageHeader)page)->pd_multi_base);
nulls[8] = false;
nulls[9] = false;
nulls[10] = false;
} else {
values[8] = ShortTransactionIdGetDatum(page->pd_prune_xid);
nulls[9] = true;
nulls[10] = true;
}
/* Build and return the tuple. */
// 使用元组描述符和数据构建元组并返回
tuple = heap_form_tuple(tupdesc, values, nulls);
result = HeapTupleGetDatum(tuple);
PG_RETURN_DATUM(result);
}
使用gsql查看页头信息，可查看lsn，行指针的末尾为60，元组的起始位为8032，与上面查询到的页面数据一致，页大小为8192等。
cc1=# select * from page_header(get_raw_page('m',0));
lsn | tli | flags | lower | upper | special | pagesize | version | prune_xid
-----------+-----+-------+-------+-------+---------+----------+---------+-----------
0/2F6FD10 | 0 | 0 | 60 | 8032 | 8192 | 8192 | 6 | 14429
(1 row)
- 函数 page_compress_meta(IN relation_name bytea,IN blkno int4,IN blknum int4,OUT compress_meta text)
获取压缩的元数据，关联rawpage.cpp page_compress_meta方法。
// arg1: relation name
// arg2: start blockno
// arg3: number of parsing block, default is 1
//
PG_FUNCTION_INFO_V1(page_compress_meta);
Datum page_compress_meta(PG_FUNCTION_ARGS)
{
text* relname = PG_GETARG_TEXT_P(0);
uint32 blkno = PG_GETARG_UINT32(1);
uint32 blknum = PG_GETARG_UINT32(2);
uint32 real_blknum;
RangeVar* relrv = NULL;
Relation rel;
StringInfo output = makeStringInfo();
super_user();
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
check(rel);
// get block number, then check start blkno and input blknum
//
real_blknum = RelationGetNumberOfBlocks(rel);
if (blkno >= real_blknum) {
// 校验起始页编号
appendStringInfo(output, "start blkno %u >= real block number %u \n", blkno, real_blknum);
} else {
if (blkno + blknum > real_blknum) { // blknum是否重新赋值
blknum = real_blknum - blkno;
}
appendStringInfo(output,
"relfinenode (space=%u, db=%u, rel=%u) \n",
rel->rd_node.spcNode, // 表空间 oid
rel->rd_node.dbNode, // 数据库 oid
rel->rd_node.relNode); // relation oid
// parse and output the compression metadata
// 读取各页面数据，解析压缩的元数据
for (uint32 i = 0; i < blknum; ++i) {
char* raw_page = read_raw_page(rel, MAIN_FORKNUM, blkno + i);
appendStringInfo(output, "Block #%d \n", blkno + i);
parse_compress_meta(output, raw_page, rel);
appendStringInfo(output, "\n");
pfree(raw_page);
}
}
relation_close(rel, AccessShareLock);
// 构建返回值
bytea* dumpVal = (bytea*)palloc(VARHDRSZ + output->len);
SET_VARSIZE(dumpVal, VARHDRSZ + output->len);
memcpy(VARDATA(dumpVal), output->data, output->len);
pfree(output->data);
pfree(output);
PG_RETURN_TEXT_P(dumpVal);
}
static void parse_compress_meta(StringInfo outputBuf, char* page_content, Relation rel)
{
PageHeader page_header = (PageHeader)page_content;
// 非压缩页面
if (!PageIsCompressed(page_header)) {
appendStringInfo(outputBuf, "\t This page is not compressed \n");
return;
}
char* start = page_content + page_header->pd_special;
// char* current = start;
int size = PageGetSpecialSize(page_header); // pd_special大小
TupleDesc desc = RelationGetDescr(rel); // 描述元组的结构
Form_pg_attribute* att = desc->attrs; // 元组属性的数组
int attrno;
int attrnum = desc->natts; // 元组属性的大小
int cmprsOff = 0;
void* metaInfo = NULL;
char mode = 0;
// 遍历并解析
for (attrno = 0; attrno < attrnum && cmprsOff < size; ++attrno) {
Form_pg_attribute thisatt = att[attrno];
int metaSize = 0;
metaInfo = PageCompress::FetchAttrCmprMeta(start + cmprsOff, thisatt->attlen, &metaSize, &mode);
switch (mode) {
case CMPR_DELTA: {
DeltaCmprMeta* deltaInfo = (DeltaCmprMeta*)metaInfo;
appendStringInfo(outputBuf, "\t Col #%d: Delta, attr-len %d, min-val ", attrno, deltaInfo->bytes);
int min_val_start = cmprsOff + sizeof(mode) + sizeof(unsigned char);
formatBytes(outputBuf, (start + min_val_start), thisatt->attlen);
appendStringInfo(outputBuf, "\n");
break;
}
case CMPR_DICT: {
DictCmprMeta* dictMeta = (DictCmprMeta*)metaInfo;
appendStringInfo(outputBuf, "\t Col #%d: dictionary, items %d \n", attrno, dictMeta->dictItemNum);
for (int i = 0; i < dictMeta->dictItemNum; ++i) {
DictItemData* item = dictMeta->dictItems + i;
appendStringInfo(outputBuf, "\t\t Item #%d, len %d, data ", i, item->itemSize);
formatBytes(outputBuf, item->itemData, item->itemSize);
appendStringInfo(outputBuf, "\n");
}
break;
}
case CMPR_PREFIX: {
PrefixCmprMeta* prefixMeta = (PrefixCmprMeta*)metaInfo;
appendStringInfo(outputBuf, "\t Col #%d: prefix, len %d, data ", attrno, prefixMeta->len);
formatBytes(outputBuf, prefixMeta->prefixStr, prefixMeta->len);
appendStringInfo(outputBuf, "\n");
break;
}
case CMPR_NUMSTR: {
appendStringInfo(outputBuf, "\t Col #%d: number string compression \n", attrno);
break;
}
case CMPR_NONE: {
appendStringInfo(outputBuf, "\t Col #%d: none compression \n", attrno);
break;
}
}
cmprsOff += metaSize;
}
}
- 函数 page_compress_meta_usage(OUT help text)
打印函数 page_compress_meta的帮助信息。
cc1=# select page_compress_meta_usage();
page_compress_meta_usage
---------------------------------------------------
usage: page_compress_meta name blkno blknum +
+
name, relation/table name, only for heap +
blkno, the start blockno +
blknum, how many blocks to parse +
(1 row)
cc1=#
- 函数 heap_page_items(IN page bytea,OUT lp smallint,OUT lp_off smallint,OUT lp_flags smallint,OUT lp_len smallint,OUT t_xmin xid,OUT t_xmax xid,OUT t_field3 int4,OUT t_ctid tid,OUT t_infomask2 integer,OUT t_infomask integer,OUT t_hoff smallint,OUT t_bits text,OUT t_oid oid)
显示一个堆页面上所有的行指针，关联heapfuncs.cpp的heap_page_items方法。
/*
* heap_page_items
*
* Allows inspection of line pointers and tuple headers of a heap page.
*/
PG_FUNCTION_INFO_V1(heap_page_items);
typedef struct heap_page_items_state {
TupleDesc tupd;
Page page;
uint16 offset;
} heap_page_items_state;
Datum heap_page_items(PG_FUNCTION_ARGS)
{
bytea* raw_page = PG_GETARG_BYTEA_P(0);
heap_page_items_state* inter_call_data = NULL;
FuncCallContext* fctx = NULL;
uint32 raw_page_size;
// 非超级用户报错
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use raw page functions"))));
// 页大小
raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
// 首次调用
if (SRF_IS_FIRSTCALL()) {
TupleDesc tupdesc;
MemoryContext mctx;
if (raw_page_size < SizeOfPageHeaderData)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("input page too small (%d bytes)", raw_page_size)));
// 创建一个空的FuncCallContext数据结构，并做一些其他基本的多函数调用设置（如创建一个适当的长期生存的上下文来保存跨调用数据multi_call_memory_ctx）和错误检查
fctx = SRF_FIRSTCALL_INIT();
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
inter_call_data = (heap_page_items_state*)palloc(sizeof(heap_page_items_state));
/* Build a tuple descriptor for our result type */
// 构建元组结束符
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
inter_call_data->tupd = tupdesc;
// 首个行指针offset，赋值为1
inter_call_data->offset = FirstOffsetNumber;
// 页数据
inter_call_data->page = VARDATA(raw_page);
// 页行指针最大的offset
fctx->max_calls = PageGetMaxOffsetNumber(inter_call_data->page);
fctx->user_fctx = inter_call_data;
MemoryContextSwitchTo(mctx);
}
// 多函数调用准备工作，清理TupleTableSlot
fctx = SRF_PERCALL_SETUP();
inter_call_data = (heap_page_items_state*)(fctx->user_fctx);
if (fctx->call_cntr < fctx->max_calls) {
Page page = inter_call_data->page;
HeapTuple resultTuple;
Datum result;
ItemId id;
Datum values[13];
bool nulls[13];
uint16 lp_offset;
uint16 lp_flags;
uint16 lp_len;
memset(nulls, 0, sizeof(nulls));
/* Extract information from the line pointer */
// 获取行指针的信息
id = PageGetItemId(page, inter_call_data->offset);
lp_offset = ItemIdGetOffset(id); // 到元组的偏移量
lp_flags = ItemIdGetFlags(id); // 状态值，0:unused, 1:used
lp_len = ItemIdGetLength(id); // 元组的字节长度
values[0] = UInt16GetDatum(inter_call_data->offset); // 行指针的偏移量
values[1] = UInt16GetDatum(lp_offset);
values[2] = UInt16GetDatum(lp_flags);
values[3] = UInt16GetDatum(lp_len);
/*
* We do just enough validity checking to make sure we don't reference
* data outside the page passed to us. The page could be corrupt in
* many other ways, but at least we won't crash.
*/
if (ItemIdHasStorage(id) && lp_len >= MinHeapTupleSize && lp_offset == MAXALIGN(lp_offset) &&
lp_offset + lp_len <= raw_page_size) {
// 行指针指向的元组存储在页面中
HeapTupleData tup;
HeapTupleHeader tuphdr;
int bits_len;
/* Extract information from the tuple header */
// 从元组头部获取信息
tuphdr = (HeapTupleHeader)PageGetItem(page, id);
tup.t_data = tuphdr;
HeapTupleCopyBaseFromPage(&tup, page);
values[4] = UInt32GetDatum(HeapTupleGetRawXmin(&tup));
values[5] = UInt32GetDatum(HeapTupleGetRawXmax(&tup));
values[6] = UInt32GetDatum(HeapTupleHeaderGetRawCommandId(tuphdr)); /* shared with xvac */
values[7] = PointerGetDatum(&tuphdr->t_ctid); // ctid
values[8] = UInt32GetDatum(tuphdr->t_infomask2);
values[9] = UInt32GetDatum(tuphdr->t_infomask);
values[10] = UInt8GetDatum(tuphdr->t_hoff);
/*
* We already checked that the item as is completely within the
* raw page passed to us, with the length given in the line
* pointer.. Let's check that t_hoff doesn't point over lp_len,
* before using it to access t_bits and oid.
*/
// 校验元组头部大小是否小于元组字节长度
if (tuphdr->t_hoff >= sizeof(HeapTupleHeader) && tuphdr->t_hoff <= lp_len) {
if (tuphdr->t_infomask & HEAP_HASNULL) {
bits_len = tuphdr->t_hoff - (((char*)tuphdr->t_bits) - ((char*)tuphdr));
values[11] = CStringGetTextDatum(bits_to_text(tuphdr->t_bits, bits_len * 8));
} else
nulls[11] = true;
if (tuphdr->t_infomask & HEAP_HASOID)
values[12] = HeapTupleHeaderGetOid(tuphdr);
else
nulls[12] = true;
} else {
nulls[11] = true;
nulls[12] = true;
}
} else {
/*
* The line pointer is not used, or it's invalid. Set the rest of
* the fields to NULL
* 行指针未使用或无效，将剩余的字段值设置为NULL
*/
int i;
for (i = 4; i <= 12; i++)
nulls[i] = true;
}
/* Build and return the result tuple. */
// 构建&返回结果元组
resultTuple = heap_form_tuple(inter_call_data->tupd, values, nulls);
result = HeapTupleGetDatum(resultTuple);
inter_call_data->offset++; // offset +1
// 设置一些状态值，将当前结果返回
SRF_RETURN_NEXT(fctx, result);
} else
// 停止多函数调用，删除多函数调用使用的相关参数，变量等
SRF_RETURN_DONE(fctx);
}
用gsql执行，可看到对应输出结果：
cc1=# SELECT * FROM heap_page_items(get_raw_page('m',0));
lp | lp_off | lp_flags | lp_len | t_xmin | t_xmax | t_field3 | t_ctid | t_infomask2 | t_infomask | t_hoff | t_bits | t_oid
----+--------+----------+--------+--------+--------+----------+--------+-------------+------------+--------+--------+-------
1 | 8160 | 1 | 28 | 14432 | 0 | 0 | (0,1) | 1 | 2304 | 24 | |
2 | 8128 | 1 | 28 | 14432 | 0 | 0 | (0,2) | 1 | 2304 | 24 | |
3 | 8096 | 1 | 28 | 14432 | 0 | 0 | (0,3) | 1 | 2304 | 24 | |
4 | 8064 | 1 | 28 | 14432 | 0 | 0 | (0,4) | 1 | 2304 | 24 | |
5 | 8032 | 1 | 28 | 14432 | 0 | 0 | (0,5) | 1 | 2304 | 24 | |
(5 rows)
cc1=# insert into m select generate_series(6,10);
INSERT 0 5
cc1=# SELECT * FROM heap_page_items(get_raw_page('m',0));
lp | lp_off | lp_flags | lp_len | t_xmin | t_xmax | t_field3 | t_ctid | t_infomask2 | t_infomask | t_hoff | t_bits | t_oid
----+--------+----------+--------+--------+--------+----------+--------+-------------+------------+--------+--------+-------
1 | 8160 | 1 | 28 | 14432 | 0 | 0 | (0,1) | 1 | 2304 | 24 | |
2 | 8128 | 1 | 28 | 14432 | 0 | 0 | (0,2) | 1 | 2304 | 24 | |
3 | 8096 | 1 | 28 | 14432 | 0 | 0 | (0,3) | 1 | 2304 | 24 | |
4 | 8064 | 1 | 28 | 14432 | 0 | 0 | (0,4) | 1 | 2304 | 24 | |
5 | 8032 | 1 | 28 | 14432 | 0 | 0 | (0,5) | 1 | 2304 | 24 | |
6 | 8000 | 1 | 28 | 14444 | 0 | 0 | (0,6) | 1 | 2048 | 24 | |
7 | 7968 | 1 | 28 | 14444 | 0 | 0 | (0,7) | 1 | 2048 | 24 | |
8 | 7936 | 1 | 28 | 14444 | 0 | 0 | (0,8) | 1 | 2048 | 24 | |
9 | 7904 | 1 | 28 | 14444 | 0 | 0 | (0,9) | 1 | 2048 | 24 | |
10 | 7872 | 1 | 28 | 14444 | 0 | 0 | (0,10) | 1 | 2048 | 24 | |
(10 rows)
cc1=#
- 函数 bt_metap(IN relname text,OUT magic int4,OUT version int4,OUT root int4,OUT level int4,OUT fastroot int4,OUT fastlevel int4)
返回关于一个B树索引元页的信息，关联btreefuncs.cpp的bt_metap方法。
/* ------------------------------------------------
* bt_metap()
*
* Get a btree's meta-page information
*
* Usage: SELECT * FROM bt_metap('t1_pkey')
* ------------------------------------------------
*/
Datum bt_metap(PG_FUNCTION_ARGS)
{
text* relname = PG_GETARG_TEXT_P(0);
Datum result;
Relation rel;
RangeVar* relrv = NULL;
BTMetaPageData* metad = NULL;
TupleDesc tupleDesc;
int j;
char* values[6];
Buffer buffer;
Page page;
HeapTuple tuple;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use pageinspect functions"))));
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
// 非btree 索引报错
if (!IS_INDEX(rel) || !IS_BTREE(rel))
elog(ERROR, "relation \"%s\" is not a btree index", RelationGetRelationName(rel));
/*
* Reject attempts to read non-local temporary relations; we would be
* likely to get wrong data since we have no visibility into the owning
* session's local buffers.
* 非本地临时表报错
*/
if (RELATION_IS_OTHER_TEMP(rel))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions")));
// 读取索引元页数据
buffer = ReadBuffer(rel, 0);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
// 从元页数据构建BTMetaPageData结构
page = BufferGetPage(buffer);
metad = BTPageGetMeta(page);
/* Build a tuple descriptor for our result type */
// 为结果类型构建元组结束符
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
// 赋值
j = 0;
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_magic);
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_version);
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_root); // 当前root所在的页编号
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_level); // 索引树的高度
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_fastroot);
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", metad->btm_fastlevel);
// 构建返回元组
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc), values);
result = HeapTupleGetDatum(tuple);
UnlockReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
PG_RETURN_DATUM(result);
}
用gsql执行：
cc1=# create table l(id int primary key);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "l_pkey" for table "l"
CREATE TABLE
cc1=# insert into l select generate_series(1,10000);
INSERT 0 10000
cc1=# analyze l;
ANALYZE
cc1=# select * from bt_metap('l_pkey');
magic | version | root | level | fastroot | fastlevel
--------+---------+------+-------+----------+-----------
340322 | 2 | 3 | 1 | 3 | 1
(1 row)
cc1=#
- 函数 bt_page_stats(IN relname text, IN blkno int4,OUT blkno int4,OUT type "char",OUT live_items int4,OUT dead_items int4,OUT avg_item_size int4,OUT page_size int4,OUT free_size int4,OUT btpo_prev int4,OUT btpo_next int4,OUT btpo int4,OUT btpo_flags int4)
返回有关 B-树索引单一页面的总计信息，关联btreefuncs.cpp的bt_page_items方法。
/* -------------------------------------------------
* GetBTPageStatistics()
*
* Collect statistics of single b-tree page
* 收集单个b-tree页面的统计信息
* -------------------------------------------------
*/
static void GetBTPageStatistics(BlockNumber blkno, Buffer buffer, BTPageStat* stat)
{
Page page = BufferGetPage(buffer);
PageHeader phdr = (PageHeader)page;
// 存储兄弟节点的指针
BTPageOpaqueInternal opaque = (BTPageOpaqueInternal)PageGetSpecialPointer(page);
int item_size = 0;
int off;
stat->blkno = blkno; // 页面编号
stat->max_avail = BLCKSZ - (BLCKSZ - phdr->pd_special + SizeOfPageHeaderData);
stat->dead_items = stat->live_items = 0; // 初始化dead items,live items
stat->page_size = PageGetPageSize(page); // 页面大小
/* page type (flags) */
if (P_ISDELETED(opaque)) { // 页已从树中删除
stat->type = 'd';
if (PageIs4BXidVersion(page))
stat->btpo.xact = opaque->btpo.xact_old;
else
stat->btpo.xact = ((BTPageOpaque)opaque)->xact;
return;
} else if (P_IGNORE(opaque)) // 空页
stat->type = 'e';
else if (P_ISLEAF(opaque)) // 叶页，即不是内页
stat->type = 'l';
else if (P_ISROOT(opaque)) // 根页面(没有父页面)
stat->type = 'r';
else
stat->type = 'i';
/* btpage opaque data */
stat->btpo_prev = opaque->btpo_prev; // 前一个页面
stat->btpo_next = opaque->btpo_next; // 后一个页面
stat->btpo.level = opaque->btpo.level;
stat->btpo_flags = opaque->btpo_flags; // 状态
stat->btpo_cycleid = opaque->btpo_cycleid;
/* count live and dead tuples, and free space */
// 计算存活元组，死元组和空闲空间
// 遍历行指针
for (off = FirstOffsetNumber; off <= PageGetMaxOffsetNumber(page); off++) {
IndexTuple itup;
ItemId id = PageGetItemId(page, off);
itup = (IndexTuple)PageGetItem(page, id);
item_size += IndexTupleSize(itup);
if (!ItemIdIsDead(id))
stat->live_items++;
else
stat->dead_items++;
}
stat->free_size = PageGetFreeSpace(page);
if ((stat->live_items + stat->dead_items) > 0)
stat->avg_item_size = item_size / (stat->live_items + stat->dead_items);
else
stat->avg_item_size = 0;
}
/* -----------------------------------------------
* bt_page_stats()
*
* Usage: SELECT * FROM bt_page_stats('t1_pkey', 1);
* -----------------------------------------------
*/
Datum bt_page_stats(PG_FUNCTION_ARGS)
{
text* relname = PG_GETARG_TEXT_P(0);
uint32 blkno = PG_GETARG_UINT32(1);
Buffer buffer;
Relation rel;
RangeVar* relrv = NULL;
Datum result;
HeapTuple tuple;
TupleDesc tupleDesc;
int j;
char* values[11];
BTPageStat stat = {0};
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use pageinspect functions"))));
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
// 非btree索引报错
if (!IS_INDEX(rel) || !IS_BTREE(rel))
elog(ERROR, "relation \"%s\" is not a btree index", RelationGetRelationName(rel));
/*
* Reject attempts to read non-local temporary relations; we would be
* likely to get wrong data since we have no visibility into the owning
* session's local buffers.
* 非本地临时表报错
*/
if (RELATION_IS_OTHER_TEMP(rel))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions")));
// 页编号为0是元页面，返回错误
if (blkno == 0)
elog(ERROR, "block 0 is a meta page");
// 检查页编号是否存在，不存在则报错
CHECK_RELATION_BLOCK_RANGE(rel, blkno);
// 读取对应编号的页数据
buffer = ReadBuffer(rel, blkno);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
/* keep compiler quiet */
// 初始化相关变量
stat.btpo_prev = stat.btpo_next = InvalidBlockNumber;
stat.btpo_flags = stat.free_size = stat.avg_item_size = 0;
// 获取页面统计信息
GetBTPageStatistics(blkno, buffer, &stat);
UnlockReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
/* Build a tuple descriptor for our result type */
// 构建元组描述符
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
j = 0;
// 赋值
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.blkno); // 页编号
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%c", stat.type); // 页类型
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.live_items); // 存活元组数
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.dead_items); // 死元组数
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.avg_item_size); // 元组平均大小
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.page_size); // 页大小
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.free_size); // 空闲空间
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.btpo_prev); // 前一个页面
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.btpo_next); // 后一个页面
values[j] = (char*)palloc(32);
if (stat.type == 'd')
snprintf(values[j++], 64, XID_FMT, stat.btpo.xact);
else
snprintf(values[j++], 32, "%d", stat.btpo.level);
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", stat.btpo_flags);
// 构建返回元组
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc), values);
result = HeapTupleGetDatum(tuple);
PG_RETURN_DATUM(result);
}
用gsql执行：
cc1=# select * from bt_page_stats('l_pkey',1);
blkno | type | live_items | dead_items | avg_item_size | page_size | free_size | btpo_prev | btpo_next | btpo | btpo_flags
-------+------+------------+------------+---------------+-----------+-----------+-----------+-----------+------+------------
1 | l | 367 | 0 | 16 | 8192 | 800 | 0 | 2 | 0 | 1
(1 row)
cc1=# select * from bt_page_stats('l_pkey',2);
blkno | type | live_items | dead_items | avg_item_size | page_size | free_size | btpo_prev | btpo_next | btpo | btpo_flags
-------+------+------------+------------+---------------+-----------+-----------+-----------+-----------+------+------------
2 | l | 367 | 0 | 16 | 8192 | 800 | 1 | 4 | 0 | 1
(1 row)
cc1=# select * from bt_page_stats('l_pkey',3);
blkno | type | live_items | dead_items | avg_item_size | page_size | free_size | btpo_prev | btpo_next | btpo | btpo_flags
-------+------+------------+------------+---------------+-----------+-----------+-----------+-----------+------+------------
3 | r | 28 | 0 | 15 | 8192 | 7588 | 0 | 0 | 1 | 2
(1 row)
cc1=# select * from bt_page_stats('l_pkey',4);
blkno | type | live_items | dead_items | avg_item_size | page_size | free_size | btpo_prev | btpo_next | btpo | btpo_flags
-------+------+------------+------------+---------------+-----------+-----------+-----------+-----------+------+------------
4 | l | 367 | 0 | 16 | 8192 | 800 | 2 | 5 | 0 | 1
(1 row)
cc1=# select * from bt_page_stats('l_pkey',5);
blkno | type | live_items | dead_items | avg_item_size | page_size | free_size | btpo_prev | btpo_next | btpo | btpo_flags
-------+------+------------+------------+---------------+-----------+-----------+-----------+-----------+------+------------
5 | l | 367 | 0 | 16 | 8192 | 800 | 4 | 6 | 0 | 1
(1 row)
cc1=#
- 函数 bt_page_items(IN relname text, IN blkno int4,OUT itemoffset smallint,OUT ctid tid,OUT itemlen smallint,OUT nulls bool,OUT vars bool,OUT data text)
返回一个 B-树索引页面上项的所有细节信息，关联btreefuncs.cpp的bt_page_stats方法。
/*-------------------------------------------------------
* bt_page_items()
*
* Get IndexTupleData set in a btree page
*
* Usage: SELECT * FROM bt_page_items('t1_pkey', 1);
*-------------------------------------------------------
*/
/*
* cross-call data structure for SRF
*/
struct user_args {
Page page;
OffsetNumber offset;
};
Datum bt_page_items(PG_FUNCTION_ARGS)
{
text* relname = PG_GETARG_TEXT_P(0);
uint32 blkno = PG_GETARG_UINT32(1);
Datum result;
char* values[6];
HeapTuple tuple;
FuncCallContext* fctx = NULL;
MemoryContext mctx;
struct user_args* uargs;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use pageinspect functions"))));
// 首次调用
if (SRF_IS_FIRSTCALL()) {
RangeVar* relrv = NULL;
Relation rel;
Buffer buffer;
BTPageOpaqueInternal opaque;
TupleDesc tupleDesc;
fctx = SRF_FIRSTCALL_INIT();
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = relation_openrv(relrv, AccessShareLock);
// 非btree索引报错
if (!IS_INDEX(rel) || !IS_BTREE(rel))
elog(ERROR, "relation \"%s\" is not a btree index", RelationGetRelationName(rel));
/*
* Reject attempts to read non-local temporary relations; we would be
* likely to get wrong data since we have no visibility into the
* owning session's local buffers.
* 非本地临时表报错
*/
if (RELATION_IS_OTHER_TEMP(rel))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions")));
if (blkno == 0)
elog(ERROR, "block 0 is a meta page");
// 检查页编号是否有效
CHECK_RELATION_BLOCK_RANGE(rel, blkno);
// 获取页数据
buffer = ReadBuffer(rel, blkno);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
/*
* We copy the page into local storage to avoid holding pin on the
* buffer longer than we must, and possibly failing to release it at
* all if the calling query doesn't fetch all rows.
* 复制页面数据到user_args
*/
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
uargs = (user_args*)palloc(sizeof(struct user_args));
uargs->page = (char*)palloc(BLCKSZ);
memcpy(uargs->page, BufferGetPage(buffer), BLCKSZ);
UnlockReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
uargs->offset = FirstOffsetNumber; // 初始化offset， 1
opaque = (BTPageOpaqueInternal)PageGetSpecialPointer(uargs->page);
if (P_ISDELETED(opaque))
elog(NOTICE, "page is deleted");
fctx->max_calls = PageGetMaxOffsetNumber(uargs->page); // 获取行指针数量
/* Build a tuple descriptor for our result type */
// 构建元组描述符
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
// 构建 AttInMetadata 结构
fctx->attinmeta = TupleDescGetAttInMetadata(tupleDesc);
fctx->user_fctx = uargs;
MemoryContextSwitchTo(mctx);
}
// 多函数调用设置
fctx = SRF_PERCALL_SETUP();
uargs = (user_args*)(fctx->user_fctx);
if (fctx->call_cntr < fctx->max_calls) {
ItemId id;
IndexTuple itup;
int j;
int off;
int dlen;
char* dump = NULL;
char* ptr = NULL;
id = PageGetItemId(uargs->page, uargs->offset);
if (!ItemIdIsValid(id))
elog(ERROR, "invalid ItemId");
itup = (IndexTuple)PageGetItem(uargs->page, id); // 获取索引元组
j = 0;
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", uargs->offset); // 行指针offset
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "(%u,%u)", BlockIdGetBlockNumber(&(itup->t_tid.ip_blkid)), itup->t_tid.ip_posid); // ctid
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%d", (int)IndexTupleSize(itup)); // 索引元组大小
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%c", IndexTupleHasNulls(itup) ? 't' : 'f'); // 索引元组是否存在空值
values[j] = (char*)palloc(32);
snprintf(values[j++], 32, "%c", IndexTupleHasVarwidths(itup) ? 't' : 'f'); // 索引元组是否存在var-width属性
// 索引元组数据
ptr = (char*)itup + IndexInfoFindDataOffset(itup->t_info);
dlen = IndexTupleSize(itup) - IndexInfoFindDataOffset(itup->t_info);
dump = (char*)palloc0(dlen * 3 + 1);
values[j] = dump;
for (off = 0; off < dlen; off++) {
if (off > 0)
*dump++ = ' ';
sprintf(dump, "%02x", *(ptr + off) & 0xff);
dump += 2;
}
// 构建返回元组
tuple = BuildTupleFromCStrings(fctx->attinmeta, values);
result = HeapTupleGetDatum(tuple);
uargs->offset = uargs->offset + 1;
// 设置一些状态值，将当前结果返回
SRF_RETURN_NEXT(fctx, result);
} else {
// 释放中间变量
pfree(uargs->page);
pfree(uargs);
// 停止多函数调用，删除多函数调用使用的相关参数，变量等
SRF_RETURN_DONE(fctx);
}
}
用gsql执行：
cc1=# select * from bt_page_items('l_pkey',2);
itemoffset | ctid | itemlen | nulls | vars | data
------------+---------+---------+-------+------+-------------------------
1 | (3,55) | 16 | f | f | dd 02 00 00 00 00 00 00
2 | (1,141) | 16 | f | f | 6f 01 00 00 00 00 00 00
3 | (1,142) | 16 | f | f | 70 01 00 00 00 00 00 00
4 | (1,143) | 16 | f | f | 71 01 00 00 00 00 00 00
5 | (1,144) | 16 | f | f | 72 01 00 00 00 00 00 00
6 | (1,145) | 16 | f | f | 73 01 00 00 00 00 00 00
7 | (1,146) | 16 | f | f | 74 01 00 00 00 00 00 00
8 | (1,147) | 16 | f | f | 75 01 00 00 00 00 00 00
9 | (1,148) | 16 | f | f | 76 01 00 00 00 00 00 00
10 | (1,149) | 16 | f | f | 77 01 00 00 00 00 00 00
11 | (1,150) | 16 | f | f | 78 01 00 00 00 00 00 00
12 | (1,151) | 16 | f | f | 79 01 00 00 00 00 00 00
13 | (1,152) | 16 | f | f | 7a 01 00 00 00 00 00 00
14 | (1,153) | 16 | f | f | 7b 01 00 00 00 00 00 00
15 | (1,154) | 16 | f | f | 7c 01 00 00 00 00 00 00
16 | (1,155) | 16 | f | f | 7d 01 00 00 00 00 00 00
17 | (1,156) | 16 | f | f | 7e 01 00 00 00 00 00 00
18 | (1,157) | 16 | f | f | 7f 01 00 00 00 00 00 00
19 | (1,158) | 16 | f | f | 80 01 00 00 00 00 00 00
20 | (1,159) | 16 | f | f | 81 01 00 00 00 00 00 00
21 | (1,160) | 16 | f | f | 82 01 00 00 00 00 00 00
22 | (1,161) | 16 | f | f | 83 01 00 00 00 00 00 00
23 | (1,162) | 16 | f | f | 84 01 00 00 00 00 00 00
24 | (1,163) | 16 | f | f | 85 01 00 00 00 00 00 00
25 | (1,164) | 16 | f | f | 86 01 00 00 00 00 00 00
26 | (1,165) | 16 | f | f | 87 01 00 00 00 00 00 00
27 | (1,166) | 16 | f | f | 88 01 00 00 00 00 00 00
28 | (1,167) | 16 | f | f | 89 01 00 00 00 00 00 00
29 | (1,168) | 16 | f | f | 8a 01 00 00 00 00 00 00
30 | (1,169) | 16 | f | f | 8b 01 00 00 00 00 00 00
31 | (1,170) | 16 | f | f | 8c 01 00 00 00 00 00 00
32 | (1,171) | 16 | f | f | 8d 01 00 00 00 00 00 00
33 | (1,172) | 16 | f | f | 8e 01 00 00 00 00 00 00
34 | (1,173) | 16 | f | f | 8f 01 00 00 00 00 00 00
35 | (1,174) | 16 | f | f | 90 01 00 00 00 00 00 00
36 | (1,175) | 16 | f | f | 91 01 00 00 00 00 00 00
37 | (1,176) | 16 | f | f | 92 01 00 00 00 00 00 00
38 | (1,177) | 16 | f | f | 93 01 00 00 00 00 00 00
39 | (1,178) | 16 | f | f | 94 01 00 00 00 00 00 00
40 | (1,179) | 16 | f | f | 95 01 00 00 00 00 00 00
41 | (1,180) | 16 | f | f | 96 01 00 00 00 00 00 00
42 | (1,181) | 16 | f | f | 97 01 00 00 00 00 00 00
43 | (1,182) | 16 | f | f | 98 01 00 00 00 00 00 00
44 | (1,183) | 16 | f | f | 99 01 00 00 00 00 00 00
cc1=#
- 函数 fsm_page_contents(IN page bytea)
显示FSM页面的内部节点结构，关联fsmfuncs.cpp fsm_page_contents方法。
/*
* Dumps the contents of a FSM page.
*/
PG_FUNCTION_INFO_V1(fsm_page_contents);
Datum fsm_page_contents(PG_FUNCTION_ARGS)
{
bytea* raw_page = PG_GETARG_BYTEA_P(0);
StringInfoData sinfo;
FSMPage fsmpage;
uint32 i;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use raw page functions"))));
// 获取fsm页面数据
fsmpage = (FSMPage)PageGetContents(VARDATA(raw_page));
// 初始化StringInfoData结构
initStringInfo(&sinfo);
// append每个节点的信息返回
for (i = 0; i < NodesPerPage; i++) {
if (fsmpage->fp_nodes[i] != 0)
appendStringInfo(&sinfo, "%d: %d\n", i, fsmpage->fp_nodes[i]);
}
// append "next"指针，指向页面中下一个要返回的槽
appendStringInfo(&sinfo, "fp_next_slot: %d\n", fsmpage->fp_next_slot);
PG_RETURN_TEXT_P(cstring_to_text(sinfo.data));
}
用gsql执行：
cc1=# SELECT fsm_page_contents(get_raw_page('pg_class', 'fsm', 0));
fsm_page_contents
-------------------
0: 250 +
1: 250 +
3: 250 +
7: 250 +
15: 250 +
31: 250 +
63: 250 +
127: 250 +
255: 250 +
511: 250 +
1023: 250 +
2047: 250 +
4095: 250 +
fp_next_slot: 0 +
(1 row)
cc1=#
- 函数 gin_metapage_info(IN page bytea,OUT pending_head bigint,OUT pending_tail bigint,OUT tail_free_size int4,OUT n_pending_pages bigint,OUT n_pending_tuples bigint,OUT n_total_pages bigint,OUT n_entry_pages bigint,OUT n_data_pages bigint,OUT n_entries bigint,OUT version int4)
返回有关一个 GIN索引元页的信息，关联ginfuncs.cpp gin_metapage_info方法。
Datum gin_metapage_info(PG_FUNCTION_ARGS)
{
bytea* raw_page = PG_GETARG_BYTEA_P(0);
int raw_page_size;
TupleDesc tupdesc;
Page page;
GinPageOpaque opaq;
GinMetaPageData* metadata = NULL;
HeapTuple resultTuple;
Datum values[10];
bool nulls[10];
if (!superuser())
ereport(
ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use raw page functions"))));
// 校验页大小
raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
if (raw_page_size < BLCKSZ)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("input page too small (%d bytes)", raw_page_size)));
page = VARDATA(raw_page);
// 校验是否gin索引页
opaq = (GinPageOpaque)PageGetSpecialPointer(page);
if (opaq->flags != GIN_META)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("input page is not a GIN metapage"),
errdetail("Flags %04X, expected %04X", opaq->flags, GIN_META)));
/* Build a tuple descriptor for our result type */
// 构建元组描述符
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
// 获取gin索引元数据
metadata = GinPageGetMeta(page);
memset(nulls, 0, sizeof(nulls));
values[0] = Int64GetDatum(metadata->head);
values[1] = Int64GetDatum(metadata->tail);
values[2] = Int32GetDatum(metadata->tailFreeSize);
values[3] = Int64GetDatum(metadata->nPendingPages);
values[4] = Int64GetDatum(metadata->nPendingHeapTuples);
/* statistics, updated by VACUUM */
values[5] = Int64GetDatum(metadata->nTotalPages);
values[6] = Int64GetDatum(metadata->nEntryPages);
values[7] = Int64GetDatum(metadata->nDataPages);
values[8] = Int64GetDatum(metadata->nEntries);
values[9] = Int32GetDatum(metadata->ginVersion);
/* Build and return the result tuple. */
// 构建返回元组
resultTuple = heap_form_tuple(tupdesc, values, nulls);
return HeapTupleGetDatum(resultTuple);
}
用gsql执行：
cc1=# \d+ g
Table "public.g"
Column | Type | Modifiers | Storage | Stats target | Description
--------+---------+-----------+---------+--------------+-------------
id | integer | | plain | |
Indexes:
"g_idx" gin (id) TABLESPACE pg_default
Has OIDs: no
Options: orientation=row, compression=no
cc1=# select * from gin_metapage_info(get_raw_page('g_idx',0));
pending_head | pending_tail | tail_free_size | n_pending_pages | n_pending_tuples | n_total_pages | n_entry_pages | n_data_pages | n_entries | version
--------------+--------------+----------------+-----------------+------------------+---------------+---------------+--------------+-----------+---------
2 | 2 | 8040 | 1 | 6 | 2 | 1 | 0 | 0 | 2
(1 row)
cc1=#
- 函数 gin_page_opaque_info(IN page bytea,OUT rightlink bigint,OUT maxoff int4,OUT flags text[])
返回有关一个 GIN索引不透明区域的信息，如页面类型等，关联ginfuncs.cpp gin_page_opaque_info方法。
Datum gin_page_opaque_info(PG_FUNCTION_ARGS)
{
bytea* raw_page = PG_GETARG_BYTEA_P(0);
int raw_page_size;
TupleDesc tupdesc;
Page page;
GinPageOpaque opaq;
HeapTuple resultTuple;
Datum values[3];
bool nulls[10];
Datum flags[16];
int nflags = 0;
uint16 flagbits;
if (!superuser())
ereport(
ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use raw page functions"))));
raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
if (raw_page_size < BLCKSZ)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("input page too small (%d bytes)", raw_page_size)));
page = VARDATA(raw_page);
// 获取GIN索引不透明区域的信息
opaq = (GinPageOpaque)PageGetSpecialPointer(page);
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* Convert the flags bitmask to an array of human-readable names */
// 转换标记名
flagbits = opaq->flags;
if (flagbits & GIN_DATA)
flags[nflags++] = CStringGetTextDatum("data");
if (flagbits & GIN_LEAF)
flags[nflags++] = CStringGetTextDatum("leaf"); // 叶页
if (flagbits & GIN_DELETED)
flags[nflags++] = CStringGetTextDatum("deleted");
if (flagbits & GIN_META)
flags[nflags++] = CStringGetTextDatum("meta"); // 元页
if (flagbits & GIN_LIST)
flags[nflags++] = CStringGetTextDatum("list");
if (flagbits & GIN_LIST_FULLROW)
flags[nflags++] = CStringGetTextDatum("list_fullrow");
if (flagbits & GIN_INCOMPLETE_SPLIT)
flags[nflags++] = CStringGetTextDatum("incomplete_split");
if (flagbits & GIN_COMPRESSED)
flags[nflags++] = CStringGetTextDatum("compressed");
flagbits &= ~(GIN_DATA | GIN_LEAF | GIN_DELETED | GIN_META | GIN_LIST | GIN_LIST_FULLROW | GIN_INCOMPLETE_SPLIT |
GIN_COMPRESSED);
if (flagbits) {
// flag非已知标记处理为hex值
/* any flags we don't recognize are printed in hex */
flags[nflags++] = DirectFunctionCall1(to_hex32, Int32GetDatum(flagbits));
}
memset(nulls, 0, sizeof(nulls));
values[0] = Int64GetDatum(opaq->rightlink); // 下一个页如果存在
values[1] = Int64GetDatum(opaq->maxoff);
values[2] = PointerGetDatum(construct_array(flags, nflags, TEXTOID, -1, false, 'i'));
/* Build and return the result tuple. */
// 构建返回元组
resultTuple = heap_form_tuple(tupdesc, values, nulls);
return HeapTupleGetDatum(resultTuple);
}
用gsql执行：
cc1=# SELECT * FROM gin_page_opaque_info(get_raw_page('g_idx',25));
rightlink | maxoff | flags
-----------+--------+---------------------
26 | 408 | {list,list_fullrow}
(1 row)
cc1=#
- 函数 gin_leafpage_items(IN page bytea,OUT first_tid tid,OUT nbytes int2,OUT tids tid[])
返回有关存储在一个 GIN叶子页面中的数据的信息，关联ginfuncs.cpp gin_leafpage_items方法。
typedef struct gin_leafpage_items_state {
TupleDesc tupd;
GinPostingList* seg;
GinPostingList* lastseg;
} gin_leafpage_items_state;
Datum gin_leafpage_items(PG_FUNCTION_ARGS)
{
bytea* raw_page = PG_GETARG_BYTEA_P(0);
int raw_page_size;
FuncCallContext* fctx = NULL;
gin_leafpage_items_state* inter_call_data = NULL;
if (!superuser())
ereport(
ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use raw page functions"))));
raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
// 首次调用
if (SRF_IS_FIRSTCALL()) {
TupleDesc tupdesc;
MemoryContext mctx;
Page page;
GinPageOpaque opaq;
// 校验页大小
if (raw_page_size < BLCKSZ)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("input page too small (%d bytes)", raw_page_size)));
page = VARDATA(raw_page);
// 校验不透明区域大小
if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("input page is not a valid GIN data leaf page"),
errdetail("Special size %d, expected %d",
(int)PageGetSpecialSize(page),
(int)MAXALIGN(sizeof(GinPageOpaqueData)))));
opaq = (GinPageOpaque)PageGetSpecialPointer(page);
// 非compressed GIN data leaf页报错
if (opaq->flags != (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("input page is not a compressed GIN data leaf page"),
errdetail("Flags %04X, expected %04X", opaq->flags, (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))));
// 初始化FuncCallContext数据结构
fctx = SRF_FIRSTCALL_INIT();
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
inter_call_data = (gin_leafpage_items_state*)palloc(sizeof(gin_leafpage_items_state));
/* Build a tuple descriptor for our result type */
// 构建元组描述符
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
inter_call_data->tupd = tupdesc;
// 首个porting list
inter_call_data->seg = GinDataLeafPageGetPostingList(page);
inter_call_data->lastseg =
(GinPostingList*)(((char*)inter_call_data->seg) + GinDataLeafPageGetPostingListSize(page));
fctx->user_fctx = inter_call_data;
MemoryContextSwitchTo(mctx);
}
// 多函数调用准备工作
fctx = SRF_PERCALL_SETUP();
inter_call_data = (gin_leafpage_items_state*)fctx->user_fctx;
if (inter_call_data->seg != inter_call_data->lastseg) {
GinPostingList* cur = inter_call_data->seg;
HeapTuple resultTuple;
Datum result;
Datum values[3];
bool nulls[3];
int ndecoded, i;
ItemPointer tids;
Datum* tids_datum = NULL;
memset(nulls, 0, sizeof(nulls));
values[0] = ItemPointerGetDatum(&cur->first); // 列表的第一个tid
values[1] = UInt16GetDatum(cur->nbytes); // 后面的字节数
/* build an array of decoded item pointers */
// 构建数组存储所有列表值
tids = ginPostingListDecode(cur, &ndecoded);
tids_datum = (Datum*)palloc(ndecoded * sizeof(Datum));
for (i = 0; i < ndecoded; i++)
tids_datum[i] = ItemPointerGetDatum(&tids[i]);
values[2] = PointerGetDatum(construct_array(tids_datum, ndecoded, TIDOID, sizeof(ItemPointerData), false, 's'));
pfree(tids_datum);
pfree(tids);
/* Build and return the result tuple. */
// 构建返回元组
resultTuple = heap_form_tuple(inter_call_data->tupd, values, nulls);
result = HeapTupleGetDatum(resultTuple);
inter_call_data->seg = GinNextPostingListSegment(cur);
// 设置一些状态值，将当前结果返回
SRF_RETURN_NEXT(fctx, result);
} else
// 停止多函数调用，删除多函数调用使用的相关参数，变量等
SRF_RETURN_DONE(fctx);
}
用gsql执行：
cc1=# CREATE TABLE test1 (x int, y int[]);
CREATE TABLE
cc1=# INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
INSERT 0 1
cc1=# CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
CREATE INDEX
cc1=# select * FROM gin_leafpage_items(get_raw_page('test1_y_idx',
(pg_relation_size('test1_y_idx') /
current_setting('block_size')::bigint)::int - 1));cc1(# cc1(#
-[ RECORD 1 ]-------------------------------------------------------------------------------------------
first_tid | (0,2)
nbytes | 372
tids | {"(0,2)","(0,3)","(0,4)","(0,5)","(0,6)","(0,7)","(0,8)","(0,9)","(0,10)","(0,11)","(0,12)","(0,13)","(0,14)","(0,15)","(0,16)","(0,17)","(0,18)","(0,19)","(0,20)","(0,21)
","(0,22)","(0,23)","(0,24)","(0,25)","(0,26)","(0,27)","(0,28)","(0,29)","(0,30)","(0,31)","(0,32)","(0,33)","(0,34)","(0,35)","(0,36)","(0,37)","(0,38)","(0,39)","(0,40)","(0,41)","
(0,42)","(0,43)","(0,44)","(0,45)","(0,46)","(0,47)","(0,48)","(0,49)","(0,50)","(0,51)","(0,52)","(0,53)","(0,54)","(0,55)","(0,56)","(0,57)","(0,58)","(0,59)","(0,60)","(0,61)","(0,
62)","(0,63)","(0,64)","(0,65)","(0,66)","(0,67)","(0,68)","(0,69)","(0,70)","(0,71)","(0,72)","(0,73)","(0,74)","(0,75)","(0,76)","(0,77)","(0,78)","(0,79)","(0,80)","(0,81)","(0,82)
","(0,83)","(0,84)","(0,85)","(0,86)","(0,87)","(0,88)","(0,89)","(0,90)","(0,91)","(0,92)","(0,93)","(0,94)","(0,95)","(0,96)","(0,97)","(0,98)","(0,99)","(0,100)","(0,101)","(0,102)
","(0,103)","(0,104)","(0,105)","(0,106)","(0,107)","(0,108)","(0,109)","(0,110)","(0,111)","(0,112)","(0,113)","(0,114)","(0,115)","(0,116)","(0,117)","(0,118)","(0,119)","(1,1)","(1
,2)","(1,3)","(1,4)","(1,5)","(1,6)","(1,7)","(1,8)","(1,9)","(1,10)","(1,11)","(1,12)","(1,13)","(1,14)","(1,15)","(1,16)","(1,17)","(1,18)","(1,19)","(1,20)","(1,21)","(1,22)","(1,2
3)","(1,24)","(1,25)","(1,26)","(1,27)","(1,28)","(1,29)","(1,30)","(1,31)","(1,32)","(1,33)","(1,34)","(1,35)","(1,36)","(1,37)","(1,38)","(1,39)","(1,40)","(1,41)","(1,42)","(1,43)"
,"(1,44)","(1,45)","(1,46)","(1,47)","(1,48)","(1,49)","(1,50)","(1,51)","(1,52)","(1,53)","(1,54)","(1,55)","(1,56)","(1,57)","(1,58)","(1,59)","(1,60)","(1,61)","(1,62)","(1,63)","(
1,64)","(1,65)","(1,66)","(1,67)","(1,68)","(1,69)","(1,70)","(1,71)","(1,72)","(1,73)","(1,74)","(1,75)","(1,76)","(1,77)","(1,78)","(1,79)","(1,80)","(1,81)","(1,82)","(1,83)","(1,8
4)","(1,85)","(1,86)","(1,87)","(1,88)","(1,89)","(1,90)","(1,91)","(1,92)","(1,93)","(1,94)","(1,95)","(1,96)","(1,97)","(1,98)","(1,99)","(1,100)","(1,101)","(1,102)","(1,103)","(1,
104)","(1,105)","(1,106)","(1,107)","(1,108)","(1,109)","(1,110)","(1,111)","(1,112)","(1,113)","(1,114)","(1,115)","(1,116)","(1,117)","(1,118)","(1,119)","(2,1)","(2,2)","(2,3)","(2
,4)","(2,5)","(2,6)","(2,7)","(2,8)","(2,9)","(2,10)","(2,11)","(2,12)","(2,13)","(2,14)","(2,15)","(2,16)","(2,17)","(2,18)","(2,19)","(2,20)","(2,21)","(2,22)","(2,23)","(2,24)","(2
,25)","(2,26)","(2,27)","(2,28)","(2,29)","(2,30)","(2,31)","(2,32)","(2,33)","(2,34)","(2,35)","(2,36)","(2,37)","(2,38)","(2,39)","(2,40)","(2,41)","(2,42)","(2,43)","(2,44)","(2,45
)","(2,46)","(2,47)","(2,48)","(2,49)","(2,50)","(2,51)","(2,52)","(2,53)","(2,54)","(2,55)","(2,56)","(2,57)","(2,58)","(2,59)","(2,60)","(2,61)","(2,62)","(2,63)","(2,64)","(2,65)",
"(2,66)","(2,67)","(2,68)","(2,69)","(2,70)","(2,71)","(2,72)","(2,73)","(2,74)","(2,75)","(2,76)","(2,77)","(2,78)","(2,79)","(2,80)","(2,81)","(2,82)","(2,83)","(2,84)","(2,85)","(2
,86)","(2,87)","(2,88)","(2,89)","(2,90)","(2,91)","(2,92)","(2,93)","(2,94)","(2,95)","(2,96)","(2,97)","(2,98)","(2,99)","(2,100)","(2,101)","(2,102)","(2,103)","(2,104)","(2,105)",
"(2,106)","(2,107)","(2,108)","(2,109)","(2,110)","(2,111)","(2,112)","(2,113)","(2,114)","(2,115)","(2,116)","(2,117)","(2,118)","(2,119)","(3,1)","(3,2)","(3,3)","(3,4)","(3,5)","(3
,6)","(3,7)","(3,8)","(3,9)","(3,10)","(3,11)","(3,12)","(3,13)","(3,14)"}
--More--