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Materialize any CTE that is used more than once.

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FossilOrigin-Name: ba59159fbe6b83fb6d79fbfee22d983768b0ebbaac7e99d2ac66c810e5e04100
This commit is contained in:
drh
2021-02-21 23:44:14 +00:00
parent 7601294ad3
commit a79e2a2d28
9 changed files with 117 additions and 42 deletions
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30
src/sqliteInt.h
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@@ -1137,6 +1137,7 @@ typedef struct Bitvec Bitvec;
typedef struct CollSeq CollSeq;
typedef struct Column Column;
typedef struct Cte Cte;
typedef struct CteUse CteUse;
typedef struct Db Db;
typedef struct DbFixer DbFixer;
typedef struct Schema Schema;
@@ -2941,6 +2942,7 @@ struct SrcItem {
unsigned viaCoroutine :1; /* Implemented as a co-routine */
unsigned isRecursive :1; /* True for recursive reference in WITH */
unsigned fromDDL :1; /* Comes from sqlite_schema */
unsigned isCte :1; /* This is a CTE */
} fg;
int iCursor; /* The VDBE cursor number used to access this table */
Expr *pOn; /* The ON clause of a join */
@@ -2950,7 +2952,10 @@ struct SrcItem {
char *zIndexedBy; /* Identifier from "INDEXED BY <zIndex>" clause */
ExprList *pFuncArg; /* Arguments to table-valued-function */
} u1;
Index *pIBIndex; /* Index structure corresponding to u1.zIndexedBy */
union {
Index *pIBIndex; /* Index structure corresponding to u1.zIndexedBy */
CteUse *pCteUse; /* CTE Usage info info fg.isCte is true */
} u2;
};
/*
@@ -3889,6 +3894,7 @@ struct Cte {
ExprList *pCols; /* List of explicit column names, or NULL */
Select *pSelect; /* The definition of this CTE */
const char *zCteErr; /* Error message for circular references */
CteUse *pUse; /* Usage information for this CTE */
};
/*
@@ -3901,6 +3907,26 @@ struct With {
Cte a[1]; /* For each CTE in the WITH clause.... */
};
/*
** The Cte object is not guaranteed to persist for the entire duration
** of code generation. (The query flattener or other parser tree
** edits might delete it.) The following object records information
** about each Common Table Expression that must be preserved for the
** duration of the parse.
**
** The CteUse objects are freed using sqlite3ParserAddCleanup() rather
** than sqlite3SelectDelete(), which is what enables them to persist
** until the end of code generation.
*/
struct CteUse {
int nUse; /* Number of users of this CTE */
int addrM9e; /* Start of subroutine to compute materialization */
int regRtn; /* Return address register for addrM9e subroutine */
int iCur; /* Ephemeral table holding the materialization */
LogEst nRowEst; /* Estimated number of rows in the table */
};
#ifdef SQLITE_DEBUG
/*
** An instance of the TreeView object is used for printing the content of
@@ -4889,7 +4915,7 @@ sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context*);
int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
void sqlite3ParserReset(Parse*);
void sqlite3ParserAddCleanup(Parse*,void(*)(sqlite3*,void*),void*);
void *sqlite3ParserAddCleanup(Parse*,void(*)(sqlite3*,void*),void*);
#ifdef SQLITE_ENABLE_NORMALIZE
char *sqlite3Normalize(Vdbe*, const char*);
#endif