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Enhance the code generator for INSERT INTO ... SELECT so that the SELECT

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generates output directly in the registers that INSERT INTO will be using,
in many cases, and OP_SCopy operations can thus be avoided.

FossilOrigin-Name: aa2d8b0e8154dd2f5e2c837dc11ab362b083495b
This commit is contained in:
drh
2014-02-16 01:55:49 +00:00
parent cfc6ca4179
commit 05a86c5c0f
9 changed files with 165 additions and 199 deletions
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39
src/vdbe.c
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@@ -994,6 +994,20 @@ case OP_Null: { /* out2-prerelease */
break;
}
/* Opcode: SoftNull P1 * * * *
** Synopsis: r[P1]=NULL
**
** Set register P1 to have the value NULL as seen by the OP_MakeRecord
** instruction, but do not free any string or blob memory associated with
** the register, so that if the value was a string or blob that was
** previously copied using OP_SCopy, the copies will continue to be valid.
*/
case OP_SoftNull: {
assert( pOp->p1>0 && pOp->p1<=(p->nMem-p->nCursor) );
pOut = &aMem[pOp->p1];
pOut->flags = (pOut->flags|MEM_Null)&~MEM_Undefined;
break;
}
/* Opcode: Blob P1 P2 * P4 *
** Synopsis: r[P2]=P4 (len=P1)
@@ -2909,23 +2923,17 @@ case OP_AutoCommit: {
/* Opcode: Transaction P1 P2 P3 P4 P5
**
** Begin a transaction. The transaction ends when a Commit or Rollback
** opcode is encountered. Depending on the ON CONFLICT setting, the
** transaction might also be rolled back if an error is encountered.
** Begin a transaction on database P1 if a transaction is not already
** active.
** If P2 is non-zero, then a write-transaction is started, or if a
** read-transaction is already active, it is upgraded to a write-transaction.
** If P2 is zero, then a read-transaction is started.
**
** P1 is the index of the database file on which the transaction is
** started. Index 0 is the main database file and index 1 is the
** file used for temporary tables. Indices of 2 or more are used for
** attached databases.
**
** If P2 is non-zero, then a write-transaction is started. A RESERVED lock is
** obtained on the database file when a write-transaction is started. No
** other process can start another write transaction while this transaction is
** underway. Starting a write transaction also creates a rollback journal. A
** write transaction must be started before any changes can be made to the
** database. If P2 is greater than or equal to 2 then an EXCLUSIVE lock is
** also obtained on the file.
**
** If a write-transaction is started and the Vdbe.usesStmtJournal flag is
** true (this flag is set if the Vdbe may modify more than one row and may
** throw an ABORT exception), a statement transaction may also be opened.
@@ -2936,13 +2944,16 @@ case OP_AutoCommit: {
** entire transaction. If no error is encountered, the statement transaction
** will automatically commit when the VDBE halts.
**
** If P2 is zero, then a read-lock is obtained on the database file.
**
** If P5!=0 then this opcode also checks the schema cookie against P3
** and the schema generation counter against P4.
** The cookie changes its value whenever the database schema changes.
** This operation is used to detect when that the cookie has changed
** and that the current process needs to reread the schema.
** and that the current process needs to reread the schema. If the schema
** cookie in P3 differs from the schema cookie in the database header or
** if the schema generation counter in P4 differs from the current
** generation counter, then an SQLITE_SCHEMA error is raised and execution
** halts. The sqlite3_step() wrapper function might then reprepare the
** statement and rerun it from the beginning.
*/
case OP_Transaction: {
Btree *pBt;