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Take the LIMIT clause into account when estimating the cost of sorting.

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FossilOrigin-Name: d491745cab951e0de70f1f79b7640ea8aff6e8bb
This commit is contained in:
drh
2016-02-25 16:04:59 +00:00
parent d8c22ac655
commit c3489bbf77
7 changed files with 93 additions and 59 deletions
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42
src/sqliteInt.h
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@@ -2442,6 +2442,7 @@ struct SrcList {
#define WHERE_SORTBYGROUP 0x0800 /* Support sqlite3WhereIsSorted() */
#define WHERE_REOPEN_IDX 0x1000 /* Try to use OP_ReopenIdx */
#define WHERE_ONEPASS_MULTIROW 0x2000 /* ONEPASS is ok with multiple rows */
#define WHERE_USE_LIMIT 0x4000 /* There is a constant LIMIT clause */
/* Allowed return values from sqlite3WhereIsDistinct()
*/
@@ -2520,13 +2521,13 @@ struct NameContext {
struct Select {
ExprList *pEList; /* The fields of the result */
u8 op; /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
u16 selFlags; /* Various SF_* values */
LogEst nSelectRow; /* Estimated number of result rows */
u32 selFlags; /* Various SF_* values */
int iLimit, iOffset; /* Memory registers holding LIMIT & OFFSET counters */
#if SELECTTRACE_ENABLED
char zSelName[12]; /* Symbolic name of this SELECT use for debugging */
#endif
int addrOpenEphm[2]; /* OP_OpenEphem opcodes related to this select */
u64 nSelectRow; /* Estimated number of result rows */
SrcList *pSrc; /* The FROM clause */
Expr *pWhere; /* The WHERE clause */
ExprList *pGroupBy; /* The GROUP BY clause */
@@ -2543,22 +2544,23 @@ struct Select {
** Allowed values for Select.selFlags. The "SF" prefix stands for
** "Select Flag".
*/
#define SF_Distinct 0x0001 /* Output should be DISTINCT */
#define SF_All 0x0002 /* Includes the ALL keyword */
#define SF_Resolved 0x0004 /* Identifiers have been resolved */
#define SF_Aggregate 0x0008 /* Contains aggregate functions */
#define SF_UsesEphemeral 0x0010 /* Uses the OpenEphemeral opcode */
#define SF_Expanded 0x0020 /* sqlite3SelectExpand() called on this */
#define SF_HasTypeInfo 0x0040 /* FROM subqueries have Table metadata */
#define SF_Compound 0x0080 /* Part of a compound query */
#define SF_Values 0x0100 /* Synthesized from VALUES clause */
#define SF_MultiValue 0x0200 /* Single VALUES term with multiple rows */
#define SF_NestedFrom 0x0400 /* Part of a parenthesized FROM clause */
#define SF_MaybeConvert 0x0800 /* Need convertCompoundSelectToSubquery() */
#define SF_MinMaxAgg 0x1000 /* Aggregate containing min() or max() */
#define SF_Recursive 0x2000 /* The recursive part of a recursive CTE */
#define SF_Converted 0x4000 /* By convertCompoundSelectToSubquery() */
#define SF_IncludeHidden 0x8000 /* Include hidden columns in output */
#define SF_Distinct 0x00001 /* Output should be DISTINCT */
#define SF_All 0x00002 /* Includes the ALL keyword */
#define SF_Resolved 0x00004 /* Identifiers have been resolved */
#define SF_Aggregate 0x00008 /* Contains aggregate functions */
#define SF_UsesEphemeral 0x00010 /* Uses the OpenEphemeral opcode */
#define SF_Expanded 0x00020 /* sqlite3SelectExpand() called on this */
#define SF_HasTypeInfo 0x00040 /* FROM subqueries have Table metadata */
#define SF_Compound 0x00080 /* Part of a compound query */
#define SF_Values 0x00100 /* Synthesized from VALUES clause */
#define SF_MultiValue 0x00200 /* Single VALUES term with multiple rows */
#define SF_NestedFrom 0x00400 /* Part of a parenthesized FROM clause */
#define SF_MaybeConvert 0x00800 /* Need convertCompoundSelectToSubquery() */
#define SF_MinMaxAgg 0x01000 /* Aggregate containing min() or max() */
#define SF_Recursive 0x02000 /* The recursive part of a recursive CTE */
#define SF_FixedLimit 0x04000 /* nSelectRow set by a constant LIMIT */
#define SF_Converted 0x08000 /* By convertCompoundSelectToSubquery() */
#define SF_IncludeHidden 0x10000 /* Include hidden columns in output */
/*
@@ -3489,7 +3491,7 @@ Index *sqlite3CreateIndex(Parse*,Token*,Token*,SrcList*,ExprList*,int,Token*,
void sqlite3DropIndex(Parse*, SrcList*, int);
int sqlite3Select(Parse*, Select*, SelectDest*);
Select *sqlite3SelectNew(Parse*,ExprList*,SrcList*,Expr*,ExprList*,
Expr*,ExprList*,u16,Expr*,Expr*);
Expr*,ExprList*,u32,Expr*,Expr*);
void sqlite3SelectDelete(sqlite3*, Select*);
Table *sqlite3SrcListLookup(Parse*, SrcList*);
int sqlite3IsReadOnly(Parse*, Table*, int);
@@ -3501,7 +3503,7 @@ void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
WhereInfo *sqlite3WhereBegin(Parse*,SrcList*,Expr*,ExprList*,ExprList*,u16,int);
void sqlite3WhereEnd(WhereInfo*);
u64 sqlite3WhereOutputRowCount(WhereInfo*);
LogEst sqlite3WhereOutputRowCount(WhereInfo*);
int sqlite3WhereIsDistinct(WhereInfo*);
int sqlite3WhereIsOrdered(WhereInfo*);
int sqlite3WhereIsSorted(WhereInfo*);