EDB*Plus的client_encoding问题
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[作者 高健@博客园 [email protected]]
我的PPAS下，edb数据库的Encoding是 UTF8：
edb=# \l List of databases Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+--------------+----------+-------------+-------------+-------------- -----------------
edb | enterprisedb | UTF8 | en_US.UTF-8 | en_US.UTF-8 | postgres | enterprisedb | UTF8 | en_US.UTF-8 | en_US.UTF-8 | template0 | enterprisedb | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/enterprisedb +
| | | | | enterprisedb=CTc/enterprisedb template1 | enterprisedb | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/enterprisedb +
| | | | | enterprisedb=CTc/enterprisedb (4 rows) edb=# 。
而我在postgresql.conf里面去设置 client_encoding，无论如何也无法生效。
client_encoding = sql_ascii # actually, defaults to database # encoding
重新启动后也不行：
edb=# show client_encoding; client_encoding -----------------
UTF8 (1 row) edb=#
也就是说，client_encoding的值，就算是设置了，也未必起作用。
查看社区版PostgreSQL的源代码作参考，看看是为何：
当我用psql连接到数据库时，CheckMyDatabase函数就会被执行。
我注意到其中的这一段：
/* If we have no other source of client_encoding, use server encoding */ SetConfigOption("client_encoding", GetDatabaseEncodingName(), PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
在准备client_encoding的时候，它用了 GetDatabaseEncodingName()函数，来返回数据库的Encoding名称。
可以认为，其实postgresql.conf里的 client_encoding的设定是没有用处的，因为内部运算的时候直接拿来了所连接的数据库的Encoding。也可以说，client_encoding是一个历史遗留问题，是PostgreSQL的开发者的失误造成的！
/* * CheckMyDatabase -- fetch information from the pg_database entry for our DB */
static void CheckMyDatabase(const char *name, bool am_superuser) { HeapTuple tup; Form_pg_database dbform; char *collate; char *ctype; /* Fetch our pg_database row normally, via syscache */ tup = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId)); if (!HeapTupleIsValid(tup)) elog(ERROR, "cache lookup failed for database %u", MyDatabaseId); dbform = (Form_pg_database) GETSTRUCT(tup); /* This recheck is strictly paranoia */
if (strcmp(name, NameStr(dbform->datname)) != 0) ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database \"%s\" has disappeared from pg_database", name), errdetail("Database OID %u now seems to belong to \"%s\".", MyDatabaseId, NameStr(dbform->datname)))); /* * Check permissions to connect to the database. * These checks are not enforced when in standalone mode, so that there is * a way to recover from disabling all access to all databases, for * example "UPDATE pg_database SET datallowconn = false;". * * We do not enforce them for autovacuum worker processes either. */
if (IsUnderPostmaster && !IsAutoVacuumWorkerProcess()) { /* * Check that the database is currently allowing connections. */
if (!dbform->datallowconn) ereport(FATAL, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("database \"%s\" is not currently accepting connections", name))); /* * Check privilege to connect to the database. (The am_superuser test * is redundant, but since we have the flag, might as well check it * and save a few cycles.) */
if (!am_superuser && pg_database_aclcheck(MyDatabaseId, GetUserId(), ACL_CONNECT) != ACLCHECK_OK) ereport(FATAL, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), errmsg("permission denied for database \"%s\"", name), errdetail("User does not have CONNECT privilege."))); /* * Check connection limit for this database. * * There is a race condition here --- we create our PGPROC before * checking for other PGPROCs. If two backends did this at about the * same time, they might both think they were over the limit, while * ideally one should succeed and one fail. Getting that to work * exactly seems more trouble than it is worth, however; instead we * just document that the connection limit is approximate. */
if (dbform->datconnlimit >= 0 &&
!am_superuser && CountDBBackends(MyDatabaseId) > dbform->datconnlimit) ereport(FATAL, (errcode(ERRCODE_TOO_MANY_CONNECTIONS), errmsg("too many connections for database \"%s\"", name))); } /* * OK, we're golden. Next to-do item is to save the encoding info out of * the pg_database tuple. */ SetDatabaseEncoding(dbform->encoding); /* Record it as a GUC internal option, too */ SetConfigOption("server_encoding", GetDatabaseEncodingName(), PGC_INTERNAL, PGC_S_OVERRIDE); /* If we have no other source of client_encoding, use server encoding */ SetConfigOption("client_encoding", GetDatabaseEncodingName(), PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT); /* assign locale variables */ collate = NameStr(dbform->datcollate); ctype = NameStr(dbform->datctype); if (pg_perm_setlocale(LC_COLLATE, collate) == NULL) ereport(FATAL, (errmsg("database locale is incompatible with operating system"), errdetail("The database was initialized with LC_COLLATE \"%s\", "
" which is not recognized by setlocale().", collate), errhint("Recreate the database with another locale or install the missing locale."))); if (pg_perm_setlocale(LC_CTYPE, ctype) == NULL) ereport(FATAL, (errmsg("database locale is incompatible with operating system"), errdetail("The database was initialized with LC_CTYPE \"%s\", "
" which is not recognized by setlocale().", ctype), errhint("Recreate the database with another locale or install the missing locale."))); /* Make the locale settings visible as GUC variables, too */ SetConfigOption("lc_collate", collate, PGC_INTERNAL, PGC_S_OVERRIDE); SetConfigOption("lc_ctype", ctype, PGC_INTERNAL, PGC_S_OVERRIDE); /* Use the right encoding in translated messages */ #ifdef ENABLE_NLS pg_bind_textdomain_codeset(textdomain(NULL)); #endif ReleaseSysCache(tup); }
[作者 高健@博客园 [email protected]]
回到上一级页面：PostgreSQL内部结构与源代码研究索引页 回到顶级页面：PostgreSQL索引页
磨砺技术珠矶，践行数据之道，追求卓越价值