Avoid allocating excessive registers for the PARTITION BY expressions when processing window functions.

FossilOrigin-Name: 180be266238e18c01f8bd52c75dd9aa3e26e553620258141cd95189a0ae59ddb

manifest

@@ -1,5 +1,5 @@
-C Remove\srows\sfrom\sthe\sephemeral\stable\sused\sby\swindow\sfunctions\sonce\sthey\sare\sno\slonger\srequired.
-D 2019-03-13T15:29:14.931
+C Avoid\sallocating\sexcessive\sregisters\sfor\sthe\sPARTITION\sBY\sexpressions\swhen\sprocessing\swindow\sfunctions.
+D 2019-03-13T17:20:27.939
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 236d2739dc3e823c3c909bca2d6cef93009bafbefd7018a8f3281074ecb92954
@@ -520,7 +520,7 @@ F src/shell.c.in 01c0cc01391d00d247fdf640052d38c267fc16d975bc4f3154a02277c232dbe
 F src/sqlite.h.in 02be315feaf20c06028aacf3b032b5e7211e9aae066284eef77b081646b43ea0
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 960f1b86c3610fa23cb6a267572a97dcf286e77aa0dd3b9b23292ffaa1ea8683
-F src/sqliteInt.h 45d85aa38f1148cb7ba514efe39f5d709456c2a5064cb228ead68c59c4628836
+F src/sqliteInt.h 67d22d548eb69608082e78195091215907e03d96caf4c692d72e9d094659b40b
 F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
 F src/status.c 46e7aec11f79dad50965a5ca5fa9de009f7d6bde08be2156f1538a0a296d4d0e
 F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@ -604,7 +604,7 @@ F src/where.c 8a207cb2ca6b99e1edb1e4bbff9b0504385a759cbf66180d1deb34d80ca4b799
 F src/whereInt.h 5f14db426ca46a83eabab1ae9aa6d4b8f27504ad35b64c290916289b1ddb2e88
 F src/wherecode.c ce7b21e1be2b981d62683fc59c4ca73a04a7ff2f1ebec23d41baf2da2349afd6
 F src/whereexpr.c 36b47f7261d6b6f1a72d774c113b74beddf6745aba1018e64b196e29db233442
-F src/window.c e05db1c6684a5ee877c930edbb7186e887bbcd756124db6dc4bf423f6f5a10fd
+F src/window.c 218582db176f7a367de9cd9c34ad969d525a49924ca75eaafd85a92773a34490
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/affinity2.test a6d901b436328bd67a79b41bb0ac2663918fe3bd
 F test/affinity3.test 6a101af2fc945ce2912f6fe54dd646018551710d
@@ -1812,7 +1812,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P b1322ffb6e63a110998068bf4f0a903028bd4fc0464ae1e517d745fb46423f39
-R ab6734715fa673e5e023d8c418a37782
+P 6ad553192051eaa0c6d929baacde2de07b93c6d09de861028bbce55a2c9bfdd3
+R 33cd2506def134f030283f97ce3c86b2
 U dan
-Z ae82d7d89959a9f160b7f989622338e5
+Z 6d870069833716bcaa0c118627808d33

manifest.uuid

@@ -1 +1 @@
-6ad553192051eaa0c6d929baacde2de07b93c6d09de861028bbce55a2c9bfdd3
+180be266238e18c01f8bd52c75dd9aa3e26e553620258141cd95189a0ae59ddb

src/sqliteInt.h

@@ -3571,8 +3571,7 @@ struct Window {
   int regResult;
   int csrApp;             /* Function cursor (used by min/max) */
   int regApp;             /* Function register (also used by min/max) */
-  int regPart;            /* First in a set of registers holding PARTITION BY
-                          ** and ORDER BY values for the window */
+  int regPart;            /* Array of registers for PARTITION BY values */
   Expr *pOwner;           /* Expression object this window is attached to */
   int nBufferCol;         /* Number of columns in buffer table */
   int iArgCol;            /* Offset of first argument for this function */

src/window.c

@@ -1118,12 +1118,14 @@ int sqlite3WindowCompare(Parse *pParse, Window *p1, Window *p2){
 void sqlite3WindowCodeInit(Parse *pParse, Window *pMWin){
   Window *pWin;
   Vdbe *v = sqlite3GetVdbe(pParse);
-  int nPart = (pMWin->pPartition ? pMWin->pPartition->nExpr : 0);
-  nPart += (pMWin->pOrderBy ? pMWin->pOrderBy->nExpr : 0);
-  if( nPart ){
+
+  /* Allocate registers to use for PARTITION BY values, if any. Initialize
+  ** said registers to NULL.  */
+  if( pMWin->pPartition ){
+    int nExpr = pMWin->pPartition->nExpr;
     pMWin->regPart = pParse->nMem+1;
-    pParse->nMem += nPart;
-    sqlite3VdbeAddOp3(v, OP_Null, 0, pMWin->regPart, pMWin->regPart+nPart-1);
+    pParse->nMem += nExpr;
+    sqlite3VdbeAddOp3(v, OP_Null, 0, pMWin->regPart, pMWin->regPart+nExpr-1);
   }
 
   pMWin->regFirst = ++pParse->nMem;
@@ -2111,6 +2113,8 @@ Window *sqlite3WindowListDup(sqlite3 *db, Window *p){
 **         RETURN_ROW
 **       }
 **
+** The text above leaves out many details. Refer to the code and comments
+** below for a more complete picture.
 */
 void sqlite3WindowCodeStep(
   Parse *pParse,                  /* Parse context */
@@ -2302,8 +2306,6 @@ void sqlite3WindowCodeStep(
   sqlite3VdbeAddOp2(v, OP_Integer, 0, pMWin->regFirst);
   sqlite3VdbeAddOp2(v, OP_Goto, 0, lblWhereEnd);
 
-  /* Begin generating SECOND_ROW_CODE */
-  VdbeModuleComment((pParse->pVdbe, "Begin WindowCodeStep.SECOND_ROW"));
   sqlite3VdbeJumpHere(v, addrIfNot);
   if( regPeer ){
     windowIfNewPeer(pParse, pOrderBy, regNewPeer, regPeer, lblWhereEnd);
@@ -2354,7 +2356,6 @@ void sqlite3WindowCodeStep(
       }
     }
   }
-  VdbeModuleComment((pParse->pVdbe, "End WindowCodeStep.SECOND_ROW"));
 
   /* End of the main input loop */
   sqlite3VdbeResolveLabel(v, lblWhereEnd);
@@ -2366,7 +2367,6 @@ void sqlite3WindowCodeStep(
     sqlite3VdbeJumpHere(v, addrGosubFlush);
   }
 
-  VdbeModuleComment((pParse->pVdbe, "Begin WindowCodeStep.FLUSH"));
   addrEmpty = sqlite3VdbeAddOp1(v, OP_Rewind, csrWrite);
   if( pMWin->eEnd==TK_PRECEDING ){
     windowCodeOp(&s, WINDOW_AGGSTEP, regEnd, 0);
@@ -2413,7 +2413,6 @@ void sqlite3WindowCodeStep(
 
   sqlite3VdbeAddOp1(v, OP_ResetSorter, s.current.csr);
   sqlite3VdbeAddOp2(v, OP_Integer, 1, pMWin->regFirst);
-  VdbeModuleComment((pParse->pVdbe, "End WindowCodeStep.FLUSH"));
   if( pMWin->pPartition ){
     sqlite3VdbeChangeP1(v, addrInteger, sqlite3VdbeCurrentAddr(v));
     sqlite3VdbeAddOp1(v, OP_Return, regFlushPart);