Using the columnconversion functions of Oracle GoldenGate, you can manipulate source valuesinto the appropriate format for target columns. These functions enable you to manipulatenumbers and characters, perform tests, extract parameter values, return environmentinformation, and more.
Summary ofcolumn-conversion functions
This summary isorganized according to the types of processing that can be performed with theOracle GoldenGate functions. An alphabetical reference begins on page 431.
Table 43 Performing tests
Function Description
CASE Selects a valuedepending on a series of value tests.
EVAL Selects a value based ona series of independent tests.
IF Selectsone of two values depending on whether a conditional statement
returns TRUE or FALSE.
Table 44 Handling missing columns
Function Description
COLSTAT Returns an indicatorthat a column is MISSING, NULL, or INVALID.
COLTEST Performs conditionalcalculations to test whether a column is PRESENT,
MISSING, NULL,or INVALID.
Table 45 Working with dates
Function Description
DATE Returns a date and timebased on the format passed into the source column.
DATEDIFF Returns the difference between two dates ordatetimes.
DATENOW Returnsthe current date and time.
Table 46 Performing arithmeticcalculations
Function Description
COMPUTE Returnsthe result of an arithmetic expression.
Table 47 Working with strings
Function Description
NUMBIN Converts a binary stringinto a number.
NUMSTR Converts a string into anumber.
STRCAT Concatenates one or morestrings.
STRCMP Compares two strings.
STREXT Extracts a portion of astring.
STREQ Determines whether ornot two strings are equal.
STRFIND Finds the occurrence ofa string within a string.
STRLEN Returns the length of astring.
STRLTRIM Trims leading spaces.
STRNCAT Concatenates one or morestrings to a maximum length.
STRNCMP Compares two stringsbased on a specified number of characters.
STRNUM Converts a number into astring.
STRRTRIM Trims trailing spaces.
STRSUB Substitutes one stringfor another.
STRTRIM Trimsleading and trailing spaces.
STRUP Changes a string to uppercase.
VALONEOF Comparesa string or string column to a list of values.
Table 48 Other functions
Function Description
BINARY Maintainssource binary data as binary data in the target column
when the sourcecolumn is defined as a character column.
BINTOHEX Convertsa binary string to a hexadecimal string.
GETENV Returnsenvironmental information.
GETVAL Extractsparameters from a stored procedure as input to a FILTER
or COLMAP clause.
HEXTOBIN Converts a hexadecimal stringto a binary string.
HIGHVAL | LOWVAL Constrains a value to a high or low value.
RANGE Dividesrows into multiple groups of data for parallel processing.
TOKEN Retrievestoken data from a trail record header.
1. FETCHCOLS--抓取所需要的列
Use FETCHCOLS and FETCHCOLSEXCEPT to fetch column values from the database when the valuesare not present in the transaction log record. Use this option if the databaseuses compressed updates (where column values are not logged unless theychanged), but you need to ensure that other columnvalues required for FILTER operationsare available.
● FETCHCOLSfetchesthe specified column(s).
● FETCHCOLSEXCEPTfetchesall columns except those specified. For tables with numerous columns, FETCHCOLSEXCEPT may be more efficient than listing eachcolumn with FETCHCOLS.
Syntax TABLE
, {FETCHCOLS | FETCHCOLSEXCEPT}( [, ...]) ;
TABLEGUARD.TEST, FETCHCOLS (col_1, col_2, col_3)
2. SQLEXEC--执行sql、procedure
Use SQLEXEC to execute aSQL stored procedure or query from within a MAPstatement
during Oracle GoldenGate processing. SQLEXEC enables OracleGoldenGate to communicate directly with the database to perform any functionsupported by the database. The database function can be part of thesynchronization process, such as retrieving values for column conversion, or itcan be independent of extracting or replicating data.
When used within a MAP statement, theprocedure or query that is executed can accept input parameters from source ortarget rows and pass output parameters.
NOTE A query or procedure must be structuredcorrectly when executing a SQLEXEC statement. If Replicat encounters a problemwith the query or procedure, the process will immediately abend, regardless ofany error-handling rules that are in place.
Syntax Procedures:
SQLEXEC (
SPNAME
[, ID]
{, PARAMS | NOPARAMS}
[,
)
Syntax Queries:
SQLEXEC (
ID
, QUERY“”
{, PARAMS| NOPARAMS}
[,
)
--源端获得id，通过tokens写入trail，一同传到目标端
, sqlexec(id ifid , query "select gh. SEQ_CMS_INFOS_ID.nextval id from dual" ,noparams)
, tokens(tk_ifid = ifid.id)
--目标端执行sql获得id，映射到列
, sqlexec(id icid , query "select GUARD.SEQ_CMSBIZTAG_ID.nextval id fromdual", noparams)
, colmap(id = icid.id)
--带参数的sqlexec
, sqlexec(id ctimeb , query "select create_time from epb.v_booking where epb_id =:veidb" , params (veidb=epb_id))
3. FILTER--条件筛选
Use FILTER to select orexclude records based on a numeric value. Afilter expression can use conditional operators, Oracle GoldenGatecolumn-conversion functions, or both.
NOTETo filter based on a string, use a string function or usethe WHERE option.
Separate all FILTER componentswith commas.
filter后面的条件只能为数字，即与数字作比较。若是其他如字符类型，可以用where来进行筛选。
Syntax MAP
, TARGET , FILTER (
[, ON INSERT | ON UPDATE| ON DELETE]
[, IGNORE INSERT | IGNORE UPDATE |IGNORE DELETE]
,
[, RAISEERROR ]
);
--选出info_type中以MOBILE开头的数据（@STRFIND查找数据位置）
, FILTER(@STRFIND(info_type,"MOBILE") = 1)
4. WHERE—条件筛选
Use WHEREto selectrecords based on a conditional statement. For more information on using a WHERE clause and thecolumn data that can be used, see the Oracle GoldenGateWindows and UNIXAdministrator’s Guide.
Oracle GoldenGate does not support WHERE for columnsthat have a multi-byte character set or a character set that is incompatiblewith the character set of the local operating system.
Literal strings used in WHERE must be enclosed within double quotesunless the USEANSISQLQUOTES parameter is used in the GLOBALSfile. Thisparameter enforces SQL-92 rules for identifiers and literals.
Syntax MAP
, TARGET
,
WHERE ();
-- where后面可以直接进行column test，@NULL, @PRESENT, @ABSENT (column isnull, present or absent in the record).
--选出info_type中以MOBILE开头的数据（@STRFIND查找数据位置）
, where (@STRFIND (info_type, "MOBILE") = 1)
--选出info_status为9的数据
, where (info_status = "9" );
5. assumetargetdefs—源端与目标端表结构相同
Valid for Replicat
Use the ASSUMETARGETDEFSparameter whenthe source and target tables specified with a MAPstatement haveidentical column structure, such as when synchronizing a hot site. It directsOracle GoldenGate not to look up source structures from a source-definitionsfile.
If source and target tables do nothave the same structure, use the SOURCEDEFSparameter instead of ASSUMETARGETDEFS. See“SOURCEDEFS” on page 330.
To find out what makes source andtarget tables identical or different in Oracle GoldenGate terms, see“Associating replicated data with metadata” in the Oracle GoldenGateWindowsand UNIX Administrator’s Guide.
Default None
Syntax ASSUMETARGETDEFS
在replicat中配置，目标端与源端的表结构完全相同，用了此参数就不会去寻找源定义文件了。
如果源端与目标端的表结构不同，那么就需要使用SOURCEDEFS参数。
6. SOURCEDEFS--源端与目标端的表结构异构
Valid for Extract data pump and Replicat.
Use the SOURCEDEFS parameter to specify the name of a file thatcontains definitions of source tables or files. Source definitions are requiredwhen using Oracle GoldenGate to replicate data between heterogeneous source andtargets. Use SOURCEDEFS for one or more of thefollowing processes, depending on your Oracle GoldenGate configuration:
● A Replicat process on the target system
● A data pump on a source or intermediarysystem.
To generate thesource-definitions file, use the DEFGEN utility.Transfer the file to the intermediary or target system before starting a datapump or Replicat.
You can have multiple SOURCEDEFS statements in the parameter file if more thanone source-definitions file will be used, for example if each SOURCEDEFS file holds the definitions for a distinctapplication.
See also ASSUMETARGETDEFS on page 127.
For more informationabout how Oracle GoldenGate make use of metadata, see the Oracle GoldenGateWindowsand UNIX Administrator’s Guide.
ERROR OGG-00513 Oracle GoldenGate Delivery for Oracle, repgh.prm: Table with SOURCEDEF cannot have DDLoperations (table [GUARD.APP_INFO]). Either remove SOURCEDEF or filter outtable from DDL operations.
Use REPERRORto specify anerror and a response that together control how Replicat responds to the errorwhen executing the MAP statement. You can use REPERROR at the MAP level to overrideand supplement global error handling rules set with the REPERROR parameter at theroot level of the parameter file. Multiple REPERRORstatements canbe applied to the same MAP statement toenable automatic, comprehensive management of errors and interruption-freereplication processing.
Use COLMAPto explicitlymap source columns to target columns that have different names or to specifydefault column mapping when source and target names are identical. COLMAP providesinstructions for selecting, translating, and moving column data.
NOTETo create global rules for column mapping acrossall tables in subsequent MAP statements, use the COLMATCH parameter.
Use TOKENSto define auser token and associate it with data. Tokens enable you to extract and storedata within the user token area of a trail record header. Token data can be retrievedand used in many ways to customize the way that Oracle GoldenGate delivers
data. For example, you can use token data in column maps,stored procedures called by SQLEXEC, or macros.
To use the defined token data intarget tables, use the @TOKEN column-conversionfunction in the COLMAP clause of a Replicat MAP statement. The @TOKEN function mapsthe name of a token to a target column.
Do not use this option for tablesbeing processed in pass-through mode by a data-pump Extract group.
Use the @GETENV functionto return information about the Oracle GoldenGate environment.
You can use the information as input into thefollowing:
● Stored procedures or queries (with SQLEXEC)
● Column maps (with the COLMAP option of TABLE or MAP)
● User tokens (defined with the TOKENS option of TABLE andmapped to target columns by
means of the @TOKENS function)
● The GET_ENV_VALUEuserexit function (see page 505)
--返回当前时间
@getenv("GGHEADER", "COMMITTIMESTAMP")
--返回OGG的操作系统用户
@GETENV("GGENVIRONMENT", "OSUSERNAME"),
16. @COLTEST--列测试，一般与@IF一起用
Use the @COLTEST function toenable conditional calculations by testing for one or more column conditions.If a condition is satisfied, @COLTEST returns TRUE. To performthe conditional calculation, use the @IF function.
Use the @COLSTAT function toreturn an indicator to Extract or Replicat that a column is missing, null, or invalid.The indicator can be used as part of a larger manipulation formula that usesadditional conversion functions.
Use the @STRFINDfunction todetermine the position of a string within a string column or else return zeroif the string is not found. Optionally, @STRFINDcan accept astarting position within the string.
This function does not support NCHARorNVARCHAR data types.
Syntax @STRFIND (, “search string>” [,< begin position>])
--查找info_type中以MOBILE开头的数据
, FILTER(@STRFIND(info_type,"MOBILE") = 1)
Example Assuming thestring for the ACCT column is ABC123ABC, the followingare possible results.
Function statement Result
@STRFIND (ACCT,"23") 5
@STRFIND (ACCT,"ZZ") 0
@STRFIND (ACCT,"ABC", 2) 7 (because thesearch started at the second character)
public interface IStack<T> {
//元素出栈，并返回出栈元素
public T pop();
//元素入栈
public void push(T element);
//获取栈顶元素
public T peek();
//判断栈是否为空
public boolean isEmpty
