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In PRAGMA optimize, scale back the analysis_limit when many different tables

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and indexes must be scanned.

FossilOrigin-Name: 636615358aebfef80a657d09f15f608df9e64882b2aaa5574ce31a4f1c71fd70
This commit is contained in:
drh
2024-02-19 19:56:40 +00:00
parent f40da9226d
commit 74b0aad09f
3 changed files with 28 additions and 8 deletions
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22
src/pragma.c
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@@ -2460,7 +2460,7 @@ void sqlite3Pragma(
** of the current connection.
**
** (5) One or more of the following is true:
** (5a) One or mroe indexes on the table lacks an entry
** (5a) One or more indexes on the table lacks an entry
** in the sqlite_stat1 table. (Same as 4a)
** (5b) The number of rows in the table has increased or decreased by
** 10-fold. In other words, the current size of the table is
@@ -2484,6 +2484,8 @@ void sqlite3Pragma(
u32 opMask; /* Mask of operations to perform */
int nLimit; /* Analysis limit to use */
int nCheck = 0; /* Number of tables to be optimized */
int nBtree = 0; /* Number of btrees to scan */
int nIndex; /* Number of indexes on the current table */
if( zRight ){
opMask = (u32)sqlite3Atoi(zRight);
@@ -2518,7 +2520,9 @@ void sqlite3Pragma(
** indicate a new, unanalyzed index
*/
szThreshold = pTab->nRowLogEst;
nIndex = 0;
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
nIndex++;
if( !pIdx->hasStat1 ){
szThreshold = -1; /* Always analyze if any index lacks statistics */
break;
@@ -2545,6 +2549,7 @@ void sqlite3Pragma(
** transaction for efficiency */
sqlite3BeginWriteOperation(pParse, 0, iDb);
}
nBtree += nIndex+1;
/* Reanalyze if the table is 10 times larger or smaller than
** the last analysis. Unconditional reanalysis if there are
@@ -2572,6 +2577,21 @@ void sqlite3Pragma(
}
}
sqlite3VdbeAddOp0(v, OP_Expire);
/* In a schema with a large number of tables and indexes, scale back
** the analysis_limit to avoid excess run-time in the worst case.
*/
if( !db->mallocFailed && nBtree>100 ){
int iAddr, iEnd;
VdbeOp *aOp;
int nLimit = 100*SQLITE_DEFAULT_OPTIMIZE_LIMIT/nBtree;
if( nLimit<100 ) nLimit = 100;
aOp = sqlite3VdbeGetOp(v, 0);
iEnd = sqlite3VdbeCurrentAddr(v);
for(iAddr=0; iAddr<iEnd; iAddr++){
if( aOp[iAddr].opcode==OP_SqlExec ) aOp[iAddr].p2 = nLimit;
}
}
break;
}