Cause the ANALYZE command to build sqlite_stat1 table entries for empty tables

with the assumption that such tables really contain 10 elements.  This gives
better query plans for tables that are truely empty, but is likely to cause
problems in legacy systems, so the change is kept off trunk.  Some TCL tests
fail on this check-in due to the new stat1 entries.

FossilOrigin-Name: c81f260c2d4791e40f74c86927a4e9efb79a9d241a66476e4af35c7bbe37a49c

diff --git a/manifest b/manifest
index bb8b35571f8b5cacc981c5aa1d14699018cb5938..6a1735f0dce55812baf5813d72fb08a006b8fdce 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sthe\sSQLITE_DEFAULT_ROWEST\scompile-time\soption\sfor\schanging\sthe\sestimated\nnumber\sof\srows\sin\stables\sthat\slack\ssqlite_stat1\sentries.
-D 2017-06-06T18:20:43.972
+C Cause\sthe\sANALYZE\scommand\sto\sbuild\ssqlite_stat1\stable\sentries\sfor\sempty\stables\nwith\sthe\sassumption\sthat\ssuch\stables\sreally\scontain\s10\selements.\s\sThis\sgives\nbetter\squery\splans\sfor\stables\sthat\sare\struely\sempty,\sbut\sis\slikely\sto\scause\nproblems\sin\slegacy\ssystems,\sso\sthe\schange\sis\skept\soff\strunk.\s\sSome\sTCL\stests\nfail\son\sthis\scheck-in\sdue\sto\sthe\snew\sstat1\sentries.
+D 2017-06-07T10:55:02.135
 F Makefile.in 1cc758ce3374a32425e4d130c2fe7b026b20de5b8843243de75f087c0a2661fb
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 8eeb80162074004e906b53d7340a12a14c471a83743aab975947e95ce061efcc
@@ -342,7 +342,7 @@ F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
 F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
 F src/alter.c 3b23977620ce9662ac54443f65b87ba996e36121
-F src/analyze.c 0d0ccf7520a201d8747ea2f02c92c26e26f801bc161f714f27b9f7630dde0421
+F src/analyze.c 62a35801482e72faf30f5ccfc690837d5873ad358f93459e1aff1f13e0dbfd8d
 F src/attach.c 8c476f8bd5d2afe11d925f890d30e527e5b0ce43
 F src/auth.c 79f96c6f33bf0e5da8d1c282cee5ebb1852bb8a6ccca3e485d7c459b035d9c3c
 F src/backup.c faf17e60b43233c214aae6a8179d24503a61e83b
@@ -503,8 +503,8 @@ F test/alter3.test 4d79934d812eaeacc6f22781a080f8cfe012fdc3
 F test/alter4.test b6d7b86860111864f6cddb54af313f5862dda23b
 F test/altermalloc.test e81ac9657ed25c6c5bb09bebfa5a047cd8e4acfc
 F test/amatch1.test b5ae7065f042b7f4c1c922933f4700add50cdb9f
-F test/analyze.test 3eb35a4af972f98422e5dc0586501b17d103d321
-F test/analyze3.test 1dccda46a6c374018af617fba00bfe297a61d442
+F test/analyze.test 0e043e6595e404871327a75cb017b671098ad4406d298665d83e8e3b575ee6c7
+F test/analyze3.test d35cffa940a742c8102f128e945084580afd673c0b73ad29984e1fa7ab737c03
 F test/analyze4.test eff2df19b8dd84529966420f29ea52edc6b56213
 F test/analyze5.test 765c4e284aa69ca172772aa940946f55629bc8c4
 F test/analyze6.test f1c552ce39cca4ec922a7e4e0e5d0203d6b3281f
@@ -1582,7 +1582,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 9eea3670e77e2f831b7c00ae2d65a5583f9cad626d9ab286f92582ef29ecd4e3
-R de51f7d1edc1449c33df63cd75f44fee
+P 234ede26e30f20e6c33002739ed8be35dbfb5c77700bd857ff31072b9b7df347
+R 084bdc3fdc2ada1f3649d659e3fd2491
+T *branch * analyze-empty-tables
+T *sym-analyze-empty-tables *
+T -sym-trunk *
 U drh
-Z db2906277b1736b6942b7d17ecf808c4
+Z 01ebfe5fb16bb5cd6e6a41ca8b6d6232

diff --git a/manifest.uuid b/manifest.uuid
index 914bd0da819b9c50fdac394f8262b813db9bd929..8bb7fcd4b4d47392e375a0b68351bf8d2097e951 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-234ede26e30f20e6c33002739ed8be35dbfb5c77700bd857ff31072b9b7df347
\ No newline at end of file
+c81f260c2d4791e40f74c86927a4e9efb79a9d241a66476e4af35c7bbe37a49c
\ No newline at end of file

diff --git a/src/analyze.c b/src/analyze.c
index 495cc954accdc25a2c7efc2ff994c6eab63da9ae..11e3be2166bf2c5a96719164500bb21c23fb7bd4 100644 (file)
--- a/src/analyze.c
+++ b/src/analyze.c
@@ -875,14 +875,14 @@ static void statGet(
       return;
     }
 
-    sqlite3_snprintf(24, zRet, "%llu", (u64)p->nRow);
+    /* Never let the estimated number of rows be less than 10 */
+    sqlite3_snprintf(24, zRet, "%llu", MAX((u64)p->nRow, 10));
     z = zRet + sqlite3Strlen30(zRet);
     for(i=0; i<p->nKeyCol; i++){
       u64 nDistinct = p->current.anDLt[i] + 1;
       u64 iVal = (p->nRow + nDistinct - 1) / nDistinct;
       sqlite3_snprintf(24, z, " %llu", iVal);
       z += sqlite3Strlen30(z);
-      assert( p->current.anEq[i] );
     }
     assert( z[0]=='\0' && z>zRet );
 
@@ -984,7 +984,6 @@ static void analyzeOneTable(
   int iTabCur;                 /* Table cursor */
   Vdbe *v;                     /* The virtual machine being built up */
   int i;                       /* Loop counter */
-  int jZeroRows = -1;          /* Jump from here if number of rows is zero */
   int iDb;                     /* Index of database containing pTab */
   u8 needTableCnt = 1;         /* True to count the table */
   int regNewRowid = iMem++;    /* Rowid for the inserted record */
@@ -1219,6 +1218,7 @@ static void analyzeOneTable(
     sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, addrNextRow); VdbeCoverage(v);
 
     /* Add the entry to the stat1 table. */
+    sqlite3VdbeJumpHere(v, addrRewind);
     callStatGet(v, regStat4, STAT_GET_STAT1, regStat1);
     assert( "BBB"[0]==SQLITE_AFF_TEXT );
     sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0);
@@ -1241,6 +1241,8 @@ static void analyzeOneTable(
 
       pParse->nMem = MAX(pParse->nMem, regCol+nCol);
 
+      addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur);
+      VdbeCoverage(v);
       addrNext = sqlite3VdbeCurrentAddr(v);
       callStatGet(v, regStat4, STAT_GET_ROWID, regSampleRowid);
       addrIsNull = sqlite3VdbeAddOp1(v, OP_IsNull, regSampleRowid);
@@ -1266,11 +1268,11 @@ static void analyzeOneTable(
       sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regTemp, regNewRowid);
       sqlite3VdbeAddOp2(v, OP_Goto, 1, addrNext); /* P1==1 for end-of-loop */
       sqlite3VdbeJumpHere(v, addrIsNull);
+      sqlite3VdbeJumpHere(v, addrRewind);
     }
 #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
 
     /* End of analysis */
-    sqlite3VdbeJumpHere(v, addrRewind);
   }
 
 
@@ -1280,14 +1282,13 @@ static void analyzeOneTable(
   if( pOnlyIdx==0 && needTableCnt ){
     VdbeComment((v, "%s", pTab->zName));
     sqlite3VdbeAddOp2(v, OP_Count, iTabCur, regStat1);
-    jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1); VdbeCoverage(v);
+    sqlite3VdbeAddOp2(v, OP_AddImm, regStat1, 10);
     sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
     assert( "BBB"[0]==SQLITE_AFF_TEXT );
     sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0);
     sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
     sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regTemp, regNewRowid);
     sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
-    sqlite3VdbeJumpHere(v, jZeroRows);
   }
 }
 

diff --git a/test/analyze.test b/test/analyze.test
index af277cc83527792bd28e6247349d19203637c22c..87f0dc816c360f1eb385ea4242fcab42c862c5b9 100644 (file)
--- a/test/analyze.test
+++ b/test/analyze.test
@@ -96,7 +96,7 @@ do_test analyze-1.11 {
   execsql {
     SELECT * FROM sqlite_stat1
   }
-} {}
+} {t1 {} 0}
 do_test analyze-1.12 {
   catchsql {
     ANALYZE t1;
@@ -106,10 +106,10 @@ do_test analyze-1.13 {
   execsql {
     SELECT * FROM sqlite_stat1
   }
-} {}
+} {t1 {} 0}
 
-# Create some indices that can be analyzed.  But do not yet add
-# data.  Without data in the tables, no analysis is done.
+# Create some indices that can be analyzed. 
+# Zero sqlite_stat1 entries are created.
 #
 do_test analyze-2.1 {
   execsql {
@@ -117,21 +117,21 @@ do_test analyze-2.1 {
     ANALYZE main.t1;
     SELECT * FROM sqlite_stat1 ORDER BY idx;
   }
-} {}
+} {t1 t1i1 {0 0}}
 do_test analyze-2.2 {
   execsql {
     CREATE INDEX t1i2 ON t1(b);
     ANALYZE t1;
     SELECT * FROM sqlite_stat1 ORDER BY idx;
   }
-} {}
+} {t1 t1i1 {0 0} t1 t1i2 {0 0}}
 do_test analyze-2.3 {
   execsql {
     CREATE INDEX t1i3 ON t1(a,b);
     ANALYZE main;
     SELECT * FROM sqlite_stat1 ORDER BY idx;
   }
-} {}
+} {t1 t1i1 {0 0} t1 t1i2 {0 0} t1 t1i3 {0 0 0}}
 
 # Start adding data to the table.  Verify that the analysis
 # is done correctly.

diff --git a/test/analyze3.test b/test/analyze3.test
index 2fb558d16a285708f13185c21bc27aff19930546..eebc77b20dbe4386861b531ce18b7ee36c9aacc8 100644 (file)
--- a/test/analyze3.test
+++ b/test/analyze3.test
@@ -698,6 +698,6 @@ do_execsql_test 7.2 {
   INSERT INTO sqlite_stat1(tbl,idx,stat) VALUES('t1','t1a','12000');
   INSERT INTO sqlite_stat1(tbl,idx,stat) VALUES('t1','t1a','12000');
   ANALYZE sqlite_master;
-}
+} {t1 t1a {0 0}}
 
 finish_test