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Change the recursive common table expression algorithm to use a queue instead

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of a pair of tables.  Runs about 25% faster on the sudoku solver query. 
The OP_SwapCursors opcode is no longer required.  The current implementation
uses just a fifo, but the plan is to change it into a queue that will support 
ORDER BY and LIMIT in a recursive query.

FossilOrigin-Name: b2671e1133d2f1fbd36e7cd4b86d6cc7b528aa97
This commit is contained in:
drh
2014-01-21 22:25:45 +00:00
parent 8561c81ed6
commit e73f059093
6 changed files with 76 additions and 86 deletions
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6
src/shell.c
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@@ -1177,7 +1177,7 @@ static int str_in_array(const char *zStr, const char **azArray){
**
** * For each "Goto", if the jump destination is earlier in the program
** and ends on one of:
** Yield SeekGt SeekLt RowSetRead
** Yield SeekGt SeekLt RowSetRead Rewind
** then indent all opcodes between the earlier instruction
** and "Goto" by 2 spaces.
*/
@@ -1189,7 +1189,7 @@ static void explain_data_prepare(struct callback_data *p, sqlite3_stmt *pSql){
int iOp; /* Index of operation in p->aiIndent[] */
const char *azNext[] = { "Next", "Prev", "VPrev", "VNext", "SorterNext", 0 };
const char *azYield[] = { "Yield", "SeekLt", "SeekGt", "RowSetRead", 0 };
const char *azYield[] = { "Yield", "SeekLt", "SeekGt", "RowSetRead", "Rewind", 0 };
const char *azGoto[] = { "Goto", 0 };
/* Try to figure out if this is really an EXPLAIN statement. If this
@@ -1226,7 +1226,7 @@ static void explain_data_prepare(struct callback_data *p, sqlite3_stmt *pSql){
for(i=p2op; i<iOp; i++) p->aiIndent[i] += 2;
}
if( str_in_array(zOp, azGoto) && p2op<p->nIndent && abYield[p2op] ){
for(i=p2op; i<iOp; i++) p->aiIndent[i] += 2;
for(i=p2op+1; i<iOp; i++) p->aiIndent[i] += 2;
}
}