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Optimize the degenerate case of a FROM clause table name enclosed all by

itself inside parentheses.  Generate code as if the parentheses did not
exist, rather than the old behavior of manifesting the parenthesized table
into a transient table.  Also, tag every FROM-clause SELECT subquery that is
generated by a parenthesized FROM-clause expression using the SF_NestedFrom
flag.  The new SF_NestedFrom flag is not yet used for anything.

FossilOrigin-Name: 7fecced466d86a66b0b751c5b5608141e134fe2d
This commit is contained in:
drh
2012-12-18 19:36:11 +00:00
parent 92689d2869
commit 832ee3d4cc
7 changed files with 59 additions and 18 deletions

View File

@@ -2102,6 +2102,7 @@ struct Select {
#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 */
/*
@@ -2814,7 +2815,7 @@ 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*,int,Expr*,Expr*);
Expr*,ExprList*,u16,Expr*,Expr*);
void sqlite3SelectDelete(sqlite3*, Select*);
Table *sqlite3SrcListLookup(Parse*, SrcList*);
int sqlite3IsReadOnly(Parse*, Table*, int);