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When doing an UPDATE or DELETE using a multi-column index where only a few

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of the earlier columns of the index are useful for the index lookup,
postpone doing the main table seek until after all WHERE clause constraints
have been evaluated, in case those constraints can be covered by unused
later terms of the index, thus avoiding unnecessary main table seeks.

FossilOrigin-Name: 0ecda433718f0bc973078099b19955dcfb0dcd15b68455e53156ac708e9d92e5
This commit is contained in:
dan
2020-08-17 21:03:53 +00:00
parent 9539a09634
commit 296f59ae54
12 changed files with 95 additions and 54 deletions
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5
src/sqliteInt.h
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@@ -2716,9 +2716,9 @@ struct SrcList {
#define WHERE_DISTINCTBY 0x0080 /* pOrderby is really a DISTINCT clause */
#define WHERE_WANT_DISTINCT 0x0100 /* All output needs to be distinct */
#define WHERE_SORTBYGROUP 0x0200 /* Support sqlite3WhereIsSorted() */
#define WHERE_SEEK_TABLE 0x0400 /* Do not defer seeks on main table */
/* 0x0400 not currently used */
#define WHERE_ORDERBY_LIMIT 0x0800 /* ORDERBY+LIMIT on the inner loop */
#define WHERE_SEEK_UNIQ_TABLE 0x1000 /* Do not defer seeks if unique */
/* 0x1000 not currently used */
/* 0x2000 not currently used */
#define WHERE_USE_LIMIT 0x4000 /* Use the LIMIT in cost estimates */
/* 0x8000 not currently used */
@@ -3998,6 +3998,7 @@ int sqlite3WhereOkOnePass(WhereInfo*, int*);
#define ONEPASS_OFF 0 /* Use of ONEPASS not allowed */
#define ONEPASS_SINGLE 1 /* ONEPASS valid for a single row update */
#define ONEPASS_MULTI 2 /* ONEPASS is valid for multiple rows */
int sqlite3WhereUsesDeferredSeek(WhereInfo*);
void sqlite3ExprCodeLoadIndexColumn(Parse*, Index*, int, int, int);
int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int, u8);
void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int);