From: drh <>
Date: Thu, 13 Oct 2022 12:47:33 +0000 (+0000)
Subject: Proposed optimization to the IS NULL and NOT NULL operators that avoids
X-Git-Tag: version-3.40.0~164^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e995d2c226e2b65c5e40cd238415bdfeb0936e8c;p=thirdparty%2Fsqlite.git

Proposed optimization to the IS NULL and NOT NULL operators that avoids
loading the entire content of larges strings and BLOBs.  Response to
[forum:/info/3c08d4715dc05b00|forum post 3c08d4715dc05b00].

FossilOrigin-Name: 45f171565442f9fd6574fb93ae7abe83c168b20be68af42531bc55571450d3ab
---

diff --git a/manifest b/manifest
index d95623c883..507552e771 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Updates\sto\sthe\sfuzzer\squery\sinvariant\schecker\s-\stracking\schanges\smade\nover\sin\sdbsqlfuzz.
-D 2022-10-12T18:40:25.766
+C Proposed\soptimization\sto\sthe\sIS\sNULL\sand\sNOT\sNULL\soperators\sthat\savoids\nloading\sthe\sentire\scontent\sof\slarges\sstrings\sand\sBLOBs.\s\sResponse\sto\n[forum:/info/3c08d4715dc05b00|forum\spost\s3c08d4715dc05b00].
+D 2022-10-13T12:47:33.470
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -570,7 +570,7 @@ F src/date.c 94ce83b4cd848a387680a5f920c9018c16655db778c4d36525af0a0f34679ac5
 F src/dbpage.c 5808e91bc27fa3981b028000f8fadfdc10ce9e59a34ce7dc4e035a69be3906ec
 F src/dbstat.c 861e08690fcb0f2ee1165eff0060ea8d4f3e2ea10f80dab7d32ad70443a6ff2d
 F src/delete.c 86573edae75e3d3e9a8b590d87db8e47222103029df4f3e11fa56044459b514e
-F src/expr.c 1cbdd76eeedb729ea9060df03e3e6b74a302784a13bfa38794a8194f894641ea
+F src/expr.c d199850a925665df7f8ac29fa938909f65a2bd32354aa206aa8c25fc74ff3d3d
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 722f20779f5342a787922deded3628d8c74b5249cab04098cf17ee2f2aaff002
 F src/func.c 8f72e88cccdee22185133c10f96ccd61dc34c5ea4b1fa9a73c237ef59b2e64f1
@@ -613,7 +613,7 @@ F src/parse.y 8e67d820030d2655b9942ffe61c1e7e6b96cea2f2f72183533299393907d0564
 F src/pcache.c f4268f7f73c6a3db12ce22fd25bc68dc42315d19599414ab1207d7cf32f79197
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c dee95e3cd2b61e6512dc814c5ab76d5eb36f0bfc9441dbb4260fccc0d12bbddc
-F src/pragma.c 444f596c9e9123d19451ad762917f0f7545e4acecb10f67e09a19f01289cefce
+F src/pragma.c 41430ca04735cc8e5d003bfd9315eadede3ec326e50805cc81bcf34e46601292
 F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
 F src/prepare.c 1b02be0441eda4579471fea097f678effcbb77ef0c39ab3f703c837822bcd674
 F src/printf.c e99ee9741e79ae3873458146f59644276657340385ade4e76a5f5d1c25793764
@@ -693,10 +693,10 @@ F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
 F src/util.c 0be191521ff6d2805995f4910f0b6231b42843678b2efdc1abecaf39929a673f
 F src/vacuum.c bb346170b0b54c6683bba4a5983aea40485597fdf605c87ec8bc2e199fe88cd8
 F src/vdbe.c 4e51ba30edcdcec171fdb1db1133147ea1084d8b6842bc601b174e8a0e4b3b7f
-F src/vdbe.h 64619af62603dc3c4f5ff6ff6d2c8f389abd667a29ce6007ed44bd22b3211cd0
+F src/vdbe.h 58675f47dcf3105bab182c3ad3726efd60ffd003e954386904ac9107d0d2b743
 F src/vdbeInt.h 17b7461ffcf9ee760d1341731715a419f6b8c763089a7ece25c2e8098d702b3f
 F src/vdbeapi.c 1e8713d0b653acb43cd1bdf579c40e005c4844ea90f414f065946a83db3c27fb
-F src/vdbeaux.c c719cebaffa75e166f16a405b3dee96e7150d60fc563ab2dea716b60c6a51312
+F src/vdbeaux.c 3468ba4e9910fc6659030ea1a3f523f3bdf16396dab28a836f7f36c27c5aa771
 F src/vdbeblob.c 5e61ce31aca17db8fb60395407457a8c1c7fb471dde405e0cd675974611dcfcd
 F src/vdbemem.c 6cfed43758d57b6e3b99d9cdedfeccd86e45a07e427b22d8487cbdbebb6c522a
 F src/vdbesort.c 43756031ca7430f7aec3ef904824a7883c4ede783e51f280d99b9b65c0796e35
@@ -2034,8 +2034,11 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 368fa6b25bc803ded7c1a0184615980902657879370caec22ceea42496ec0566
-R b6417444abfe9dc882e90feaa0e7d85d
+P 4ca16a304ad10fbb48f78b4384b347fe883e1a4f222f113ac981e89845c3e113
+R f35663338c50b8e03d89b8b5f5341f38
+T *branch * isnull-opt
+T *sym-isnull-opt *
+T -sym-trunk *
 U drh
-Z 6e9d8b3a258c07649344995d3cb09455
+Z 5002c0678afa100b4df523686944d5c0
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index ca633fd6b3..97f10acb71 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-4ca16a304ad10fbb48f78b4384b347fe883e1a4f222f113ac981e89845c3e113
\ No newline at end of file
+45f171565442f9fd6574fb93ae7abe83c168b20be68af42531bc55571450d3ab
\ No newline at end of file
diff --git a/src/expr.c b/src/expr.c
index baa0fe6476..bceb5efb08 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -5241,6 +5241,7 @@ void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
       assert( TK_ISNULL==OP_IsNull );   testcase( op==TK_ISNULL );
       assert( TK_NOTNULL==OP_NotNull ); testcase( op==TK_NOTNULL );
       r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      sqlite3VdbeTypeofColumn(v, r1);
       sqlite3VdbeAddOp2(v, op, r1, dest);
       VdbeCoverageIf(v, op==TK_ISNULL);
       VdbeCoverageIf(v, op==TK_NOTNULL);
@@ -5415,6 +5416,7 @@ void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
     case TK_ISNULL:
     case TK_NOTNULL: {
       r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
+      sqlite3VdbeTypeofColumn(v, r1);
       sqlite3VdbeAddOp2(v, op, r1, dest);
       testcase( op==TK_ISNULL );   VdbeCoverageIf(v, op==TK_ISNULL);
       testcase( op==TK_NOTNULL );  VdbeCoverageIf(v, op==TK_NOTNULL);
diff --git a/src/pragma.c b/src/pragma.c
index 7976f83c6f..7aea3dd2cb 100644
--- a/src/pragma.c
+++ b/src/pragma.c
@@ -1791,9 +1791,7 @@ void sqlite3Pragma(
                 || pTab->iPKey==mxCol) ) mxCol--;
         if( mxCol>=0 ){
           sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, mxCol, 3);
-          if( sqlite3VdbeGetLastOp(v)->opcode==OP_Column ){
-            sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
-          }
+          sqlite3VdbeTypeofColumn(v, 3);
         }
 
         if( !isQuick ){
diff --git a/src/vdbe.h b/src/vdbe.h
index eb1445f1db..a244468b52 100644
--- a/src/vdbe.h
+++ b/src/vdbe.h
@@ -228,6 +228,7 @@ void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
 void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
 void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
 void sqlite3VdbeChangeP5(Vdbe*, u16 P5);
+void sqlite3VdbeTypeofColumn(Vdbe*, int);
 void sqlite3VdbeJumpHere(Vdbe*, int addr);
 void sqlite3VdbeJumpHereOrPopInst(Vdbe*, int addr);
 int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 8785e3b568..275ba6f770 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -1155,6 +1155,22 @@ void sqlite3VdbeChangeP5(Vdbe *p, u16 p5){
   if( p->nOp>0 ) p->aOp[p->nOp-1].p5 = p5;
 }
 
+/*
+** If the previous opcode is an OP_Column that delivers results
+** into register iDest, then add the OPFLAG_TYPEOF flag to that
+** opcode.
+*/
+void sqlite3VdbeTypeofColumn(Vdbe *p, int iDest){
+  if( p->nOp>0 ){
+    VdbeOp *pOp = &p->aOp[p->nOp-1];
+    if( pOp->opcode==OP_Column && pOp->p3==iDest ){
+      pOp->p5 |= OPFLAG_TYPEOFARG;
+    }
+  }else{
+    assert( p->db->mallocFailed );
+  }
+}
+
 /*
 ** Change the P2 operand of instruction addr so that it points to
 ** the address of the next instruction to be coded.