From: drh <drh@noemail.net>
Date: Tue, 7 Jun 2005 01:43:41 +0000 (+0000)
Subject: Do not open a statement journal unless absolutely necessary. (CVS 2499)
X-Git-Tag: version-3.6.10~3660
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3844990cfc5b57826a1b42ce575976bdf5679aa1;p=thirdparty%2Fsqlite.git

Do not open a statement journal unless absolutely necessary. (CVS 2499)

FossilOrigin-Name: 989573a53b58c1e959ad276119298ba2ea7448e6
---

diff --git a/manifest b/manifest
index 409ff6a532..0a392805cb 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Reference\scount\sTable\sstructures\sso\sthat\sthey\sare\snot\sdeallocated\stoo\ssoon.\nTicket\s#1210.\s(CVS\s2498)
-D 2005-06-06T21:19:57
+C Do\snot\sopen\sa\sstatement\sjournal\sunless\sabsolutely\snecessary.\s(CVS\s2499)
+D 2005-06-07T01:43:41
 F Makefile.in 8129e7f261d405db783676f9ca31e0841768c652
 F Makefile.linux-gcc 06be33b2a9ad4f005a5f42b22c4a19dab3cbb5c7
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -81,7 +81,7 @@ F src/vdbe.c e9bf69b2ba382ba23b48f98778f46d3261ae0e2c
 F src/vdbe.h 75e466d84d362b0c4498978a9d6b1e6bd32ecf3b
 F src/vdbeInt.h 4afaae2f4adcab54ad2a40dabb2e689fba7b1561
 F src/vdbeapi.c 9a9556b9d7e3a052f58de389caf69449558e7380
-F src/vdbeaux.c 84a1381023e808761d6462871ef9bd46392c5c4f
+F src/vdbeaux.c d078d96e47a391666af10fce2fbabb1ace19a4b0
 F src/vdbemem.c 48a64ae95a9edc6e8d940300dad15d70d1670398
 F src/where.c f02baff03e2a9ed7bdc36b363b8e4024a94de919
 F tclinstaller.tcl 046e3624671962dc50f0481d7c25b38ef803eb42
@@ -281,7 +281,7 @@ F www/tclsqlite.tcl 425be741b8ae664f55cb1ef2371aab0a75109cf9
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl a99cf5f6d8bd4d5537584a2b342f0fb9fa601d8b
 F www/whentouse.tcl 528299b8316726dbcc5548e9aa0648c8b1bd055b
-P 12c32f139bae3cb7ca520451bfc15f9f7d94833d
-R e390bfee5cfa27b3e5512a8098188123
+P e73d25c7419d580c47925494621df26d2fb9f27e
+R e5d64b9b0612e248c65fc146ea7ea4a7
 U drh
-Z c771356a4d5670d2ac2c478ca19855b4
+Z e7a36c84aa3464810f6e632e99f01c3c
diff --git a/manifest.uuid b/manifest.uuid
index 04b4759b39..5b41353f75 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-e73d25c7419d580c47925494621df26d2fb9f27e
\ No newline at end of file
+989573a53b58c1e959ad276119298ba2ea7448e6
\ No newline at end of file
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index be157a3c40..6ca240b9d5 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -220,6 +220,12 @@ int sqlite3VdbeOpcodeNoPush(u8 op){
 **
 ** The integer *pMaxStack is set to the maximum number of vdbe stack
 ** entries that static analysis reveals this program might need.
+**
+** This routine also does the following optimization:  It scans for
+** Halt instructions where P1==SQLITE_CONSTRAINT or P2==OE_Abort or for
+** IdxPut instructions where P2!=0.  If no such instruction is
+** found, then every Statement instruction is changed to a Noop.  In
+** this way, we avoid creating the statement journal file unnecessarily.
 */
 static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs, int *pMaxStack){
   int i;
@@ -227,6 +233,8 @@ static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs, int *pMaxStack){
   int nMaxStack = p->nOp;
   Op *pOp;
   int *aLabel = p->aLabel;
+  int doesStatementRollback = 0;
+  int hasStatementBegin = 0;
   for(pOp=p->aOp, i=p->nOp-1; i>=0; i--, pOp++){
     u8 opcode = pOp->opcode;
 
@@ -237,6 +245,16 @@ static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs, int *pMaxStack){
       if( pOp->p1>nMaxArgs ) nMaxArgs = pOp->p1;
     }else if( opcode==OP_AggFunc ){
       if( pOp->p2>nMaxArgs ) nMaxArgs = pOp->p2;
+    }else if( opcode==OP_Halt ){
+      if( pOp->p1==SQLITE_CONSTRAINT && pOp->p2==OE_Abort ){
+        doesStatementRollback = 1;
+      }
+    }else if( opcode==OP_IdxPut ){
+      if( pOp->p2 ){
+        doesStatementRollback = 1;
+      }
+    }else if( opcode==OP_Statement ){
+      hasStatementBegin = 1;
     }
 
     if( opcodeNoPush(opcode) ){
@@ -252,6 +270,19 @@ static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs, int *pMaxStack){
 
   *pMaxFuncArgs = nMaxArgs;
   *pMaxStack = nMaxStack;
+
+  /* If we never rollback a statement transaction, then statement
+  ** transactions are not needed.  So change every OP_Statement
+  ** opcode into an OP_Noop.  This avoid a call to sqlite3OsOpenExclusive()
+  ** which can be expensive on some platforms.
+  */
+  if( hasStatementBegin && !doesStatementRollback ){
+    for(pOp=p->aOp, i=p->nOp-1; i>=0; i--, pOp++){
+      if( pOp->opcode==OP_Statement ){
+        pOp->opcode = OP_Noop;
+      }
+    }
+  }
 }
 
 /*
@@ -689,7 +720,9 @@ void sqlite3VdbeMakeReady(
   /* No instruction ever pushes more than a single element onto the
   ** stack.  And the stack never grows on successive executions of the
   ** same loop.  So the total number of instructions is an upper bound
-  ** on the maximum stack depth required.
+  ** on the maximum stack depth required.  (Added later:)  The
+  ** resolveP2Values() call computes a tighter upper bound on the
+  ** stack size.
   **
   ** Allocation all the stack space we will ever need.
   */