Release 2 (8.1.6)
Part Number A76940-01
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| Oracle8i Application Developer's Guide - Large Objects (LOBs) Release 2 (8.1.6) Part Number A76940-01 |
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Internal Persistent LOBs, 37 of 42
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See:
"Use Case Model: Internal Persistent LOBs Basic Operations", for all basic operations of Internal Persistent LOBs. |
This procedure describes how to disable LOB buffering.
Enable buffering when performing a small read or write of data. Once you have completed these tasks, you must disable buffering before you can continue with any other LOB operations.
For more information, refer to "LOB Buffering Subsystem" in Chapter 5, "Advanced Topics".
See Chapter 3, "LOB Programmatic Environments" for a list of available functions in each programmatic environment. Use the following syntax references for each programmatic environment:
This scenario is part of the management of a buffering example related to Sound that is developed in this and related methods.
Examples are provided in the following programmatic environments:
/* Select the locator into a locator variable: */ sb4 select_lock_sound_locator(Lob_loc, errhp, svchp, stmthp) OCILobLocator *Lob_loc; OCIError *errhp; OCISvcCtx *svchp; OCIStmt *stmthp; { text *sqlstmt = (text *)"SELECT Sound FROM Multimedia_tab WHERE Clip_ID=1 FOR UPDATE"; OCIDefine *defnp1; checkerr (errhp, OCIStmtPrepare(stmthp, errhp, sqlstmt, (ub4)strlen((char *)sqlstmt), (ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT)); checkerr (errhp, OCIDefineByPos(stmthp, &defnp1, errhp, (ub4) 1, (dvoid *)&Lob_loc, (sb4)0, (ub2) SQLT_BLOB,(dvoid *) 0, (ub2 *) 0, (ub2 *) 0, (ub4) OCI_DEFAULT)); /* Execute the select and fetch one row: */ checkerr(errhp, OCIStmtExecute(svchp, stmthp, errhp, (ub4) 1, (ub4) 0, (CONST OCISnapshot*) 0, (OCISnapshot*) 0, (ub4) OCI_DEFAULT)); return 0; } #define MAXBUFLEN 32767 void lobBuffering (envhp, errhp, svchp, stmthp) OCIEnv *envhp; OCIError *errhp; OCISvcCtx *svchp; OCIStmt *stmthp; { OCILobLocator *Lob_loc; ub4 amt; ub4 offset; sword retval; ub1 bufp[MAXBUFLEN]; ub4 buflen; /* Allocate the locator desriptor: */ (void) OCIDescriptorAlloc((dvoid *) envhp, (dvoid **) &Lob_loc, (ub4)OCI_DTYPE_LOB, (size_t) 0, (dvoid **) 0); /* Select the BLOB: */ printf (" select a sound Lob\n"); select_lock_sound_locator(Lob_loc, errhp, svchp, stmthp); /* Open the BLOB: */ checkerr (errhp, (OCILobOpen(svchp, errhp, Lob_loc, OCI_LOB_READWRITE))); /* Enable LOB Buffering: */ printf (" enable LOB buffering\n"); checkerr (errhp, OCILobEnableBuffering(svchp, errhp, Lob_loc)); printf (" write data to LOB\n"); /* Write data into the LOB: */ amt = sizeof(bufp); buflen = sizeof(bufp); offset = 1; checkerr (errhp, OCILobWrite (svchp, errhp, Lob_loc, &amt, offset, bufp, buflen, OCI_ONE_PIECE, (dvoid *)0, (sb4 (*)(dvoid*,dvoid*,ub4*,ub1 *))0, 0, SQLCS_IMPLICIT)); /* Flush the buffer: */ printf(" flush the LOB buffers\n"); checkerr (errhp, OCILobFlushBuffer(svchp, errhp, Lob_loc, (ub4)OCI_LOB_BUFFER_FREE)); /* Disable Buffering: */ printf (" disable LOB buffering\n"); checkerr (errhp, OCILobDisableBuffering(svchp, errhp, Lob_loc)); /* Subsequent LOB WRITEs will not use the LOB Buffering Subsystem: */ /* Closing the BLOB is mandatory if you have opened it: */ checkerr (errhp, OCILobClose(svchp, errhp, Lob_loc)); /* Free resources held by the locators: */ (void) OCIDescriptorFree((dvoid *) Lob_loc, (ub4) OCI_DTYPE_LOB); return; }
IDENTIFICATION DIVISION. PROGRAM-ID. LOB-BUFFERING. ENVIRONMENT DIVISION. DATA DIVISION. WORKING-STORAGE SECTION. 01 USERID PIC X(11) VALUES "SAMP/SAMP". 01 BLOB1 SQL-BLOB. 01 BUFFER PIC X(10). 01 AMT PIC S9(9) COMP. EXEC SQL VAR BUFFER IS RAW(10) END-EXEC. EXEC SQL INCLUDE SQLCA END-EXEC. PROCEDURE DIVISION. LOB-BUFFERING. EXEC SQL WHENEVER SQLERROR DO PERFORM SQL-ERROR END-EXEC. EXEC SQL CONNECT :USERID END-EXEC. * Allocate and initialize the BLOB locator: EXEC SQL ALLOCATE :BLOB1 END-EXEC. EXEC SQL WHENEVER NOT FOUND GOTO END-OF-BLOB END-EXEC. EXEC SQL SELECT SOUND INTO :BLOB1 FROM MULTIMEDIA_TAB WHERE CLIP_ID = 1 FOR UPDATE END-EXEC. * Open the BLOB and enable buffering: EXEC SQL LOB OPEN :BLOB1 READ WRITE END-EXEC. EXEC SQL LOB ENABLE BUFFERING :BLOB1 END-EXEC. * Write some data to the BLOB: MOVE "242424" TO BUFFER. MOVE 3 TO AMT. EXEC SQL LOB WRITE :AMT FROM :BUFFER INTO :BLOB1 END-EXEC. MOVE "212121" TO BUFFER. MOVE 3 TO AMT. EXEC SQL LOB WRITE :AMT FROM :BUFFER INTO :BLOB1 END-EXEC. * Now flush the buffered writes: EXEC SQL LOB FLUSH BUFFER :BLOB1 END-EXEC. EXEC SQL LOB DISABLE BUFFERING :BLOB1 END-EXEC. EXEC SQL LOB CLOSE :BLOB1 END-EXEC. END-OF-BLOB. EXEC SQL WHENEVER NOT FOUND CONTINUE END-EXEC. EXEC SQL FREE :BLOB1 END-EXEC. EXEC SQL ROLLBACK WORK RELEASE END-EXEC. STOP RUN. SQL-ERROR. EXEC SQL WHENEVER SQLERROR CONTINUE END-EXEC. DISPLAY " ". DISPLAY "ORACLE ERROR DETECTED:". DISPLAY " ". DISPLAY SQLERRMC. EXEC SQL ROLLBACK WORK RELEASE END-EXEC. STOP RUN.
#include <oci.h> #include <stdio.h> #include <string.h> #include <sqlca.h> void Sample_Error() { EXEC SQL WHENEVER SQLERROR CONTINUE; printf("%.*s\n", sqlca.sqlerrm.sqlerrml, sqlca.sqlerrm.sqlerrmc); EXEC SQL ROLLBACK WORK RELEASE; exit(1); } #define BufferLength 256 void disableBufferingLOB_proc() { OCIBlobLocator *Lob_loc; int Amount = BufferLength; int multiple, Position = 1; /* Datatype equivalencing is mandatory for this datatype: */ char Buffer[BufferLength]; EXEC SQL VAR Buffer is RAW(BufferLength); EXEC SQL WHENEVER SQLERROR DO Sample_Error(); /* Allocate and Initialize the LOB: */ EXEC SQL ALLOCATE :Lob_loc; EXEC SQL SELECT Sound INTO :Lob_loc FROM Multimedia_tab WHERE Clip_ID = 1 FOR UPDATE; /* Enable use of the LOB Buffering Subsystem: */ EXEC SQL LOB ENABLE BUFFERING :Lob_loc; memset((void *)Buffer, 0, BufferLength); for (multiple = 0; multiple < 7; multiple++) { /* Write data to the LOB: */ EXEC SQL LOB WRITE ONE :Amount FROM :Buffer INTO :Lob_loc AT :Position; Position += BufferLength; } /* Flush the contents of the buffers and Free their resources: */ EXEC SQL LOB FLUSH BUFFER :Lob_loc FREE; /* Turn off use of the LOB Buffering Subsystem: */ EXEC SQL LOB DISABLE BUFFERING :Lob_loc; /* Write APPEND can only be done when Buffering is Disabled: */ EXEC SQL LOB WRITE APPEND ONE :Amount FROM :Buffer INTO :Lob_loc; /* Release resources held by the Locator: */ EXEC SQL FREE :Lob_loc; } void main() { char *samp = "samp/samp"; EXEC SQL CONNECT :samp; disableBufferingLOB_proc(); EXEC SQL ROLLBACK WORK RELEASE; }
Dim MySession As OraSession Dim OraDb As OraDatabase Dim OraDyn As OraDynaset, OraSound1 As OraBlob, OraSoundClone As OraBlob Set MySession = CreateObject("OracleInProcServer.XOraSession") Set OraDb = MySession.OpenDatabase("exampledb", "samp/samp", 0&) Set OraDyn = OraDb.CreateDynaset( "SELECT * FROM Multimedia_tab ORDER BY clip_id", ORADYN_DEFAULT) Set OraSound1 = OraDyn.Fields("Sound").Value 'Disable buffering: OraSound1.DisableBuffering
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