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Overview
| Comment: | Performance optimization: Avoid calling convertCompoundSelecctToSubquery() on queries that do not use the UNION, EXCEPT, or INTERSECT operators. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
c589b2fed7beabc2337d701094c22635 |
| User & Date: | drh 2013-08-05 22:05:02 |
Context
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2013-08-06
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| 07:45 | More than double the speed of the resolveP2Values() routine in vdbeaux.c by moving from an extended if-else on every opcode to a switch. Opcodes are reordered in mkopcodesh.awk to put the switched opcodes close together, for additional performance and to reduce code footprint. (check-in: 924f7e4d user: drh tags: trunk) | |
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2013-08-05
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| 22:05 | Performance optimization: Avoid calling convertCompoundSelecctToSubquery() on queries that do not use the UNION, EXCEPT, or INTERSECT operators. (check-in: c589b2fe user: drh tags: trunk) | |
| 21:54 | For the vtshim module, always zero out the xChildDestroy function pointer after calling it. (check-in: 240f7252 user: mistachkin tags: trunk) | |
Changes
Changes to src/parse.y.
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select(A) ::= oneselect(X). {A = X;}
%ifndef SQLITE_OMIT_COMPOUND_SELECT
select(A) ::= select(X) multiselect_op(Y) oneselect(Z). {
if( Z ){
Z->op = (u8)Y;
Z->pPrior = X;
}else{
sqlite3SelectDelete(pParse->db, X);
}
A = Z;
}
%type multiselect_op {int}
multiselect_op(A) ::= UNION(OP). {A = @OP;}
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> |
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select(A) ::= oneselect(X). {A = X;}
%ifndef SQLITE_OMIT_COMPOUND_SELECT
select(A) ::= select(X) multiselect_op(Y) oneselect(Z). {
if( Z ){
Z->op = (u8)Y;
Z->pPrior = X;
if( Y!=TK_ALL ) pParse->hasCompound = 1;
}else{
sqlite3SelectDelete(pParse->db, X);
}
A = Z;
}
%type multiselect_op {int}
multiselect_op(A) ::= UNION(OP). {A = @OP;}
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Changes to src/select.c.
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** If anything goes wrong, an error message is written into pParse.
** The calling function can detect the problem by looking at pParse->nErr
** and/or pParse->db->mallocFailed.
*/
static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){
Walker w;
memset(&w, 0, sizeof(w));
w.xSelectCallback = convertCompoundSelectToSubquery;
w.xExprCallback = exprWalkNoop;
w.pParse = pParse;
sqlite3WalkSelect(&w, pSelect);
w.xSelectCallback = selectExpander;
sqlite3WalkSelect(&w, pSelect);
}
#ifndef SQLITE_OMIT_SUBQUERY
/*
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** If anything goes wrong, an error message is written into pParse.
** The calling function can detect the problem by looking at pParse->nErr
** and/or pParse->db->mallocFailed.
*/
static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){
Walker w;
memset(&w, 0, sizeof(w));
w.xExprCallback = exprWalkNoop;
w.pParse = pParse;
if( pParse->hasCompound ){
w.xSelectCallback = convertCompoundSelectToSubquery;
sqlite3WalkSelect(&w, pSelect);
}
w.xSelectCallback = selectExpander;
sqlite3WalkSelect(&w, pSelect);
}
#ifndef SQLITE_OMIT_SUBQUERY
/*
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Changes to src/sqliteInt.h.
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#define SF_UsesEphemeral 0x0008 /* Uses the OpenEphemeral opcode */
#define SF_Expanded 0x0010 /* sqlite3SelectExpand() called on this */
#define SF_HasTypeInfo 0x0020 /* FROM subqueries have Table metadata */
#define SF_UseSorter 0x0040 /* Sort using a sorter */
#define SF_Values 0x0080 /* Synthesized from VALUES clause */
#define SF_Materialize 0x0100 /* Force materialization of views */
#define SF_NestedFrom 0x0200 /* Part of a parenthesized FROM clause */
/*
** The results of a select can be distributed in several ways. The
** "SRT" prefix means "SELECT Result Type".
*/
#define SRT_Union 1 /* Store result as keys in an index */
................................................................................
u8 nested; /* Number of nested calls to the parser/code generator */
u8 nTempReg; /* Number of temporary registers in aTempReg[] */
u8 nTempInUse; /* Number of aTempReg[] currently checked out */
u8 nColCache; /* Number of entries in aColCache[] */
u8 iColCache; /* Next entry in aColCache[] to replace */
u8 isMultiWrite; /* True if statement may modify/insert multiple rows */
u8 mayAbort; /* True if statement may throw an ABORT exception */
int aTempReg[8]; /* Holding area for temporary registers */
int nRangeReg; /* Size of the temporary register block */
int iRangeReg; /* First register in temporary register block */
int nErr; /* Number of errors seen */
int nTab; /* Number of previously allocated VDBE cursors */
int nMem; /* Number of memory cells used so far */
int nSet; /* Number of sets used so far */
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#define SF_UsesEphemeral 0x0008 /* Uses the OpenEphemeral opcode */ #define SF_Expanded 0x0010 /* sqlite3SelectExpand() called on this */ #define SF_HasTypeInfo 0x0020 /* FROM subqueries have Table metadata */ #define SF_UseSorter 0x0040 /* Sort using a sorter */ #define SF_Values 0x0080 /* Synthesized from VALUES clause */ #define SF_Materialize 0x0100 /* Force materialization of views */ #define SF_NestedFrom 0x0200 /* Part of a parenthesized FROM clause */ #define SF_MaybeConvert 0x0400 /* Need convertCompoundSelectToSubquery() */ /* ** The results of a select can be distributed in several ways. The ** "SRT" prefix means "SELECT Result Type". */ #define SRT_Union 1 /* Store result as keys in an index */ ................................................................................ u8 nested; /* Number of nested calls to the parser/code generator */ u8 nTempReg; /* Number of temporary registers in aTempReg[] */ u8 nTempInUse; /* Number of aTempReg[] currently checked out */ u8 nColCache; /* Number of entries in aColCache[] */ u8 iColCache; /* Next entry in aColCache[] to replace */ u8 isMultiWrite; /* True if statement may modify/insert multiple rows */ u8 mayAbort; /* True if statement may throw an ABORT exception */ u8 hasCompound; /* Need to invoke convertCompoundSelectToSubquery() */ int aTempReg[8]; /* Holding area for temporary registers */ int nRangeReg; /* Size of the temporary register block */ int iRangeReg; /* First register in temporary register block */ int nErr; /* Number of errors seen */ int nTab; /* Number of previously allocated VDBE cursors */ int nMem; /* Number of memory cells used so far */ int nSet; /* Number of sets used so far */ |