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Overview
Comment:Simplification of the VDBE bytecode for incremental blob I/O.
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SHA1: d23849f64a110e336f26282bf2b961a2a2372468
User & Date: drh 2016-01-18 00:46:11.199
Context
2016-01-18
09:08
Add a debugging function to print human-readable versions of fts5 detail=none leaf pages. (check-in: 8358af3658 user: dan tags: trunk)
00:46
Simplification of the VDBE bytecode for incremental blob I/O. (check-in: d23849f64a user: drh tags: trunk)
00:20
Fix a problem with SQLITE_TEST_REALLOC_STRESS. (check-in: 0aaf3febb0 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/vdbeblob.c.
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      ** uses it to implement the blob_read(), blob_write() and 
      ** blob_bytes() functions.
      **
      ** The sqlite3_blob_close() function finalizes the vdbe program,
      ** which closes the b-tree cursor and (possibly) commits the 
      ** transaction.
      */
      static const int iLn = VDBE_OFFSET_LINENO(3);
      static const VdbeOpList openBlob[] = {

        /* {OP_Transaction, 0, 0, 0},  // inserted separately */
        {OP_TableLock, 0, 0, 0},       /* 0: Acquire a read or write lock */
        {OP_OpenRead, 0, 0, 0},        /* 1: Open cursor 0 for reading */
        {OP_OpenWrite, 0, 0, 0},       /* 2: Open cursor 0 for read/write */
        {OP_Variable, 1, 1, 1},        /* 3: Push the rowid to the stack */
        {OP_NotExists, 0, 10, 1},      /* 4: Seek the cursor */
        {OP_Column, 0, 0, 1},          /* 5  */
        {OP_ResultRow, 1, 0, 0},       /* 6  */
        {OP_Goto, 0, 4, 0},            /* 7  */
        {OP_Close, 0, 0, 0},           /* 8  */
        {OP_Halt, 0, 0, 0},            /* 9 */
      };
      Vdbe *v = (Vdbe *)pBlob->pStmt;
      int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
      VdbeOp *aOp;

      sqlite3VdbeAddOp4Int(v, OP_Transaction, iDb, flags, 
                           pTab->pSchema->schema_cookie,








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      ** uses it to implement the blob_read(), blob_write() and 
      ** blob_bytes() functions.
      **
      ** The sqlite3_blob_close() function finalizes the vdbe program,
      ** which closes the b-tree cursor and (possibly) commits the 
      ** transaction.
      */
      static const int iLn = VDBE_OFFSET_LINENO(4);
      static const VdbeOpList openBlob[] = {
                                    /* addr/ofst */
        /* {OP_Transaction, 0, 0, 0},  // 0/   inserted separately */
        {OP_TableLock, 0, 0, 0},       /* 1/0: Acquire a read or write lock */
        {OP_OpenRead, 0, 0, 0},        /* 2/1: Open a cursor */

        {OP_Variable, 1, 1, 0},        /* 3/2: Move ?1 into reg[1] */
        {OP_NotExists, 0, 8, 1},       /* 4/3: Seek the cursor */
        {OP_Column, 0, 0, 1},          /* 5/4  */
        {OP_ResultRow, 1, 0, 0},       /* 6/5  */
        {OP_Goto, 0, 3, 0},            /* 7/6  */
        {OP_Close, 0, 0, 0},           /* 8/7  */
        {OP_Halt, 0, 0, 0},            /* 9/8  */
      };
      Vdbe *v = (Vdbe *)pBlob->pStmt;
      int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
      VdbeOp *aOp;

      sqlite3VdbeAddOp4Int(v, OP_Transaction, iDb, flags, 
                           pTab->pSchema->schema_cookie,
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        sqlite3VdbeChangeP4(v, 1, pTab->zName, P4_TRANSIENT);
      }
      if( db->mallocFailed==0 ){
#endif

        /* Remove either the OP_OpenWrite or OpenRead. Set the P2 
        ** parameter of the other to pTab->tnum.  */
        aOp[2-flags].opcode = OP_Noop;
        aOp[1+flags].p2 = pTab->tnum;
        aOp[1+flags].p3 = iDb;   

        /* Configure the number of columns. Configure the cursor to
        ** think that the table has one more column than it really
        ** does. An OP_Column to retrieve this imaginary column will
        ** always return an SQL NULL. This is useful because it means
        ** we can invoke OP_Column to fill in the vdbe cursors type 
        ** and offset cache without causing any IO.
        */
        aOp[1+flags].p4type = P4_INT32;
        aOp[1+flags].p4.i = pTab->nCol+1;
        aOp[5].p2 = pTab->nCol;

        pParse->nVar = 1;
        pParse->nMem = 1;
        pParse->nTab = 1;
        sqlite3VdbeMakeReady(v, pParse);
      }
    }








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        sqlite3VdbeChangeP4(v, 1, pTab->zName, P4_TRANSIENT);
      }
      if( db->mallocFailed==0 ){
#endif

        /* Remove either the OP_OpenWrite or OpenRead. Set the P2 
        ** parameter of the other to pTab->tnum.  */
        if( flags ) aOp[1].opcode = OP_OpenWrite;
        aOp[1].p2 = pTab->tnum;
        aOp[1].p3 = iDb;   

        /* Configure the number of columns. Configure the cursor to
        ** think that the table has one more column than it really
        ** does. An OP_Column to retrieve this imaginary column will
        ** always return an SQL NULL. This is useful because it means
        ** we can invoke OP_Column to fill in the vdbe cursors type 
        ** and offset cache without causing any IO.
        */
        aOp[1].p4type = P4_INT32;
        aOp[1].p4.i = pTab->nCol+1;
        aOp[4].p2 = pTab->nCol;

        pParse->nVar = 1;
        pParse->nMem = 1;
        pParse->nTab = 1;
        sqlite3VdbeMakeReady(v, pParse);
      }
    }
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