-C Disentangle\svariable\suse\sin\slast\scheckin
-D 2022-03-07T00:14:52.499
+C Optimizations\sto\ssqlite3BtreeIndexMoveto()\savoid\sunnecessary\scomparisons\sif\nthe\scursor\sis\salready\snear\sthe\send\sof\sthe\stable\sand\sis\snot\smoving\sfar.\s\sThis\ncase\sis\smore\scommon\sthat\syou\swould\sexpect.\s\sThe\soptimization\ssaves\salmost\n4\smillion\sCPU\scycles.
+D 2022-03-07T01:29:36.578
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c 3a925b8542eb7f2a00c1919d6dbcd252b1d2781fbc43228b33dcc03fe6cd772a
+F src/btree.c dff405cefec5a5573ca9254a6fdefcadf64fa884b575cc15cd4bb23c13b35516
F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
F src/btreeInt.h 1ca477727c5f420a8321208dc5b14d93cb46cec8f941bc49318feb0e00bc961f
F src/build.c 9891c2160886cf7e344d7e8f1f7177f9612916c7c67ffeacd64cb34a92d387a8
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P bf9d1278846dce9255f9a11ddfc5dfac1acea2eadcb20816a19d59f7bccaec0f
-R 496fa8a876df6daf353669fc02e2fc4c
-U larrybr
-Z 013bf70ae42a0fa3c911efc40e5d2bba
+P 4c3a02600f10926da1f88ddbd457bb1486e6e02dee366b5cfc89e498a10daa6f
+R d2948dadaedd31df84454fee7cf7f673
+U drh
+Z 0ebffd417ef0adafd19b87cdd03ffdc7
# Remove this line to create a well-formed Fossil manifest.
return rc;
}
+/*
+** Compare the "idx"-th cell on the page the cursor pCur is currently
+** pointing to to pIdxKey using xRecordCompare. Return negative or
+** zero if the cell is less than or equal pIdxKey. Return positive
+** if unknown.
+**
+** Return value negative: Cell at pCur[idx] less than pIdxKey
+**
+** Return value is zero: Cell at pCur[idx] equals pIdxKey
+**
+** Return value positive: Nothing is known about the relationship
+** of the cell at pCur[idx] and pIdxKey.
+**
+** This routine is part of an optimization. It is always safe to return
+** a positive value as that will cause the optimization to be skipped.
+*/
+static int indexCellCompare(
+ BtCursor *pCur,
+ int idx,
+ UnpackedRecord *pIdxKey,
+ RecordCompare xRecordCompare
+){
+ MemPage *pPage = pCur->pPage;
+ int c;
+ int nCell; /* Size of the pCell cell in bytes */
+ u8 *pCell = findCellPastPtr(pPage, idx);
+
+ nCell = pCell[0];
+ if( nCell<=pPage->max1bytePayload ){
+ /* This branch runs if the record-size field of the cell is a
+ ** single byte varint and the record fits entirely on the main
+ ** b-tree page. */
+ testcase( pCell+nCell+1==pPage->aDataEnd );
+ c = xRecordCompare(nCell, (void*)&pCell[1], pIdxKey);
+ }else if( !(pCell[1] & 0x80)
+ && (nCell = ((nCell&0x7f)<<7) + pCell[1])<=pPage->maxLocal
+ ){
+ /* The record-size field is a 2 byte varint and the record
+ ** fits entirely on the main b-tree page. */
+ testcase( pCell+nCell+2==pPage->aDataEnd );
+ c = xRecordCompare(nCell, (void*)&pCell[2], pIdxKey);
+ }else{
+ /* If the record extends into overflow pages, do not attempt
+ ** the optimization. */
+ c = 99;
+ }
+ return c;
+}
+
+/*
+** Return true (non-zero) if pCur is current pointing to the last
+** page of a table.
+*/
+static int cursorOnLastPage(BtCursor *pCur){
+ int i;
+ assert( pCur->eState==CURSOR_VALID );
+ for(i=0; i<pCur->iPage; i++){
+ MemPage *pPage = pCur->apPage[i];
+ if( pCur->aiIdx[i]<pPage->nCell ) return 0;
+ }
+ return 1;
+}
+
/* Move the cursor so that it points to an entry in an index table
** near the key pIdxKey. Return a success code.
**
|| pIdxKey->default_rc==-1
);
+
+ /* Check to see if we can skip a lot of work. Two cases:
+ **
+ ** (1) If the cursor is already pointing to the very last cell
+ ** in the table and the pIdxKey search key is greater than or
+ ** equal to that last cell, then no movement is required.
+ **
+ ** (2) If the cursor is on the last page of the table and the first
+ ** cell on that last page is less than or equal to the pIdxKey
+ ** search key, then we can start the search on the current page
+ ** without needing to go back to root.
+ */
+ if( pCur->eState==CURSOR_VALID
+ && pCur->pPage->leaf
+ && cursorOnLastPage(pCur)
+ ){
+ int c;
+ if( pCur->ix==pCur->pPage->nCell-1
+ && (c = indexCellCompare(pCur, pCur->ix, pIdxKey, xRecordCompare))<=0
+ ){
+ *pRes = c;
+ return SQLITE_OK; /* Cursor already pointing at the correct spot */
+ }
+ if( pCur->iPage>0
+ && (c = indexCellCompare(pCur, 0, pIdxKey, xRecordCompare))<=0
+ ){
+ goto bypass_moveto_root; /* Start search on the current page */
+ }
+ }
+
rc = moveToRoot(pCur);
if( rc ){
if( rc==SQLITE_EMPTY ){
}
return rc;
}
+
+bypass_moveto_root:
assert( pCur->pPage );
assert( pCur->pPage->isInit );
assert( pCur->eState==CURSOR_VALID );
assert( pCur->pPage->nCell > 0 );
- assert( pCur->iPage==0 || pCur->apPage[0]->intKey==pCur->curIntKey );
- assert( pCur->curIntKey || pIdxKey );
+ assert( pCur->curIntKey==0 );
+ assert( pIdxKey!=0 );
for(;;){
int lwr, upr, idx, c;
Pgno chldPg;
** be the right kind (index or table) of b-tree page. Otherwise
** a moveToChild() or moveToRoot() call would have detected corruption. */
assert( pPage->nCell>0 );
- assert( pPage->intKey==(pIdxKey==0) );
+ assert( pPage->intKey==0 );
lwr = 0;
upr = pPage->nCell-1;
idx = upr>>1; /* idx = (lwr+upr)/2; */
projects / thirdparty / sqlite.git / commitdiff
