Here begins an experimental branch for exploring the idea of a partial index.

This check-in is able to parse a WHERE clause on a CREATE INDEX statement, but
does not actually do anythingn with that WHERE clause yet.

FossilOrigin-Name: 6794b2dcb48b3507caccfc7867fc185818cf8291

manifest

@@ -1,5 +1,5 @@
-C Reduce\sthe\ssize\sof\sthe\sstack\srequired\sby\sthe\scodeOneLoopStart()\sfunction\sin\nwhere.c.
+C Here\sbegins\san\sexperimental\sbranch\sfor\sexploring\sthe\sidea\sof\sa\spartial\sindex.\nThis\scheck-in\sis\sable\sto\sparse\sa\sWHERE\sclause\son\sa\sCREATE\sINDEX\sstatement,\sbut\ndoes\snot\sactually\sdo\sanythingn\swith\sthat\sWHERE\sclause\syet.
-D 2013-07-30T15:10:32.747
+D 2013-07-31T18:12:26.006
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 5e41da95d92656a5004b03d3576e8b226858a28e
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -166,7 +166,7 @@ F src/btmutex.c 976f45a12e37293e32cae0281b15a21d48a8aaa7
 F src/btree.c 3f7bbfd72efb1cbf6a49515c376a031767ec930a
 F src/btree.h 6fa8a3ff2483d0bb64a9f0105a8cedeac9e00cca
 F src/btreeInt.h eecc84f02375b2bb7a44abbcbbe3747dde73edb2
-F src/build.c 42239cfd95533e4aacf4d58b4724c8f858de5ced
+F src/build.c c2903be4a825d6be0a518f87b60e0dcf878782d3
 F src/callback.c d7e46f40c3cf53c43550b7da7a1d0479910b62cc
 F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
 F src/ctime.c 4262c227bc91cecc61ae37ed3a40f08069cfa267
@@ -206,7 +206,7 @@ F src/os_unix.c 9eafa5458cf2ff684ddccff82c9bb113c7cad847
 F src/os_win.c 074cb2b9bca6a1c2bd72acf04666cdc554bfaa9b
 F src/pager.c 5d2f7475260a8588f9c441bb309d2b7eaa7ded3b
 F src/pager.h 5cb78b8e1adfd5451e600be7719f5a99d87ac3b1
-F src/parse.y 9acfcc83ddbf0cf82f0ed9582ccf0ad6c366ff37
+F src/parse.y a950b48d4363f44dd98fef8a89fbd48970ebd9ce
 F src/pcache.c f8043b433a57aba85384a531e3937a804432a346
 F src/pcache.h a5e4f5d9f5d592051d91212c5949517971ae6222
 F src/pcache1.c d23d07716de96c7c0c2503ec5051a4384c3fb938
@@ -221,7 +221,7 @@ F src/shell.c 52f975eae87c8338c4dfbf4c2842d2a0971f01fd
 F src/sqlite.h.in d6a7523d6795317aac574fccc67d9df25253771c
 F src/sqlite3.rc fea433eb0a59f4c9393c8e6d76a6e2596b1fe0c0
 F src/sqlite3ext.h 886f5a34de171002ad46fae8c36a7d8051c190fc
-F src/sqliteInt.h 89b52c053ebafa76f03bab4f0c8ee1e390eb7489
+F src/sqliteInt.h c99f22c5bda01f07e2f9a9a8cb2c0b9adeea696c
 F src/sqliteLimit.h 164b0e6749d31e0daa1a4589a169d31c0dec7b3d
 F src/status.c 7ac05a5c7017d0b9f0b4bcd701228b784f987158
 F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
@@ -589,6 +589,7 @@ F test/index2.test ee83c6b5e3173a3d7137140d945d9a5d4fdfb9d6
 F test/index3.test 423a25c789fc8cc51aaf2a4370bbdde2d9e9eed7
 F test/index4.test 2983216eb8c86ee62d9ed7cb206b5cc3331c0026
 F test/index5.test fc07c14193c0430814e7a08b5da46888ee795c33
+F test/index6.test cbd74aa8604e29982438a7defae9fadaf9605336
 F test/indexedby.test 0e959308707c808515c3a51363f7a9835027108c
 F test/indexfault.test 31d4ab9a7d2f6e9616933eb079722362a883eb1d
 F test/init.test 15c823093fdabbf7b531fe22cf037134d09587a7
@@ -1103,7 +1104,10 @@ F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
 F tool/wherecosttest.c f407dc4c79786982a475261866a161cd007947ae
 F tool/win/sqlite.vsix 97894c2790eda7b5bce3cc79cb2a8ec2fde9b3ac
-P 9e819f0f12b6f2a8e0e7a90251b3115ff1595f25
+P eb6d4278b8516e0571269049d1eaa55066f51b1a
-R 8a77f3488eeca7f033bc07ab4b9db562
+R d0aa2f7065f4153ebb66a1af4210e515
+T *branch * partial-indices
+T *sym-partial-indices *
+T -sym-trunk *
 U drh
-Z 51b3ad13ced3eb326ea64314852a899d
+Z cfed8379e8335c37848dda6e7de0acdf

manifest.uuid

@@ -1 +1 @@
-eb6d4278b8516e0571269049d1eaa55066f51b1a
+6794b2dcb48b3507caccfc7867fc185818cf8291

src/build.c

@@ -382,6 +382,7 @@ static void freeIndex(sqlite3 *db, Index *p){
 #ifndef SQLITE_OMIT_ANALYZE
   sqlite3DeleteIndexSamples(db, p);
 #endif
+  sqlite3ExprDelete(db, p->pPartIdxWhere);
   sqlite3DbFree(db, p->zColAff);
   sqlite3DbFree(db, p);
 }
@@ -1225,7 +1226,8 @@ void sqlite3AddPrimaryKey(
 #endif
   }else{
     Index *p;
-    p = sqlite3CreateIndex(pParse, 0, 0, 0, pList, onError, 0, 0, sortOrder, 0);
+    p = sqlite3CreateIndex(pParse, 0, 0, 0, pList, onError, 0, 0,
+                           0, sortOrder, 0);
     if( p ){
       p->autoIndex = 2;
     }
@@ -2483,6 +2485,7 @@ Index *sqlite3CreateIndex(
   int onError,       /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
   Token *pStart,     /* The CREATE token that begins this statement */
   Token *pEnd,       /* The ")" that closes the CREATE INDEX statement */
+  Expr *pPIWhere,    /* WHERE clause for partial indices */
   int sortOrder,     /* Sort order of primary key when pList==NULL */
   int ifNotExist     /* Omit error if index already exists */
 ){
@@ -2699,6 +2702,8 @@ Index *sqlite3CreateIndex(
   pIndex->uniqNotNull = onError==OE_Abort;
   pIndex->autoIndex = (u8)(pName==0);
   pIndex->pSchema = db->aDb[iDb].pSchema;
+  pIndex->pPartIdxWhere = pPIWhere;
+  pPIWhere = 0;
   assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 
   /* Check to see if we should honor DESC requests on index columns
@@ -2933,10 +2938,8 @@ Index *sqlite3CreateIndex(
 
   /* Clean up before exiting */
 exit_create_index:
-  if( pIndex ){
+  if( pIndex ) freeIndex(db, pIndex);
-    sqlite3DbFree(db, pIndex->zColAff);
+  sqlite3ExprDelete(db, pPIWhere);
-    sqlite3DbFree(db, pIndex);
-  }
   sqlite3ExprListDelete(db, pList);
   sqlite3SrcListDelete(db, pTblName);
   sqlite3DbFree(db, zName);

src/parse.y

@@ -300,7 +300,8 @@ ccons ::= NULL onconf.
 ccons ::= NOT NULL onconf(R).    {sqlite3AddNotNull(pParse, R);}
 ccons ::= PRIMARY KEY sortorder(Z) onconf(R) autoinc(I).
                                  {sqlite3AddPrimaryKey(pParse,0,R,I,Z);}
-ccons ::= UNIQUE onconf(R).      {sqlite3CreateIndex(pParse,0,0,0,0,R,0,0,0,0);}
+ccons ::= UNIQUE onconf(R).      {sqlite3CreateIndex(pParse,0,0,0,0,R,0,
+                                                     0,0,0,0);}
 ccons ::= CHECK LP expr(X) RP.   {sqlite3AddCheckConstraint(pParse,X.pExpr);}
 ccons ::= REFERENCES nm(T) idxlist_opt(TA) refargs(R).
                                  {sqlite3CreateForeignKey(pParse,0,&T,TA,R);}
@@ -349,7 +350,7 @@ tcons ::= CONSTRAINT nm(X).      {pParse->constraintName = X;}
 tcons ::= PRIMARY KEY LP idxlist(X) autoinc(I) RP onconf(R).
                                  {sqlite3AddPrimaryKey(pParse,X,R,I,0);}
 tcons ::= UNIQUE LP idxlist(X) RP onconf(R).
-                                 {sqlite3CreateIndex(pParse,0,0,0,X,R,0,0,0,0);}
+                               {sqlite3CreateIndex(pParse,0,0,0,X,R,0,0,0,0,0);}
 tcons ::= CHECK LP expr(E) RP onconf.
                                  {sqlite3AddCheckConstraint(pParse,E.pExpr);}
 tcons ::= FOREIGN KEY LP idxlist(FA) RP
@@ -1125,10 +1126,10 @@ nexprlist(A) ::= expr(Y).
 ///////////////////////////// The CREATE INDEX command ///////////////////////
 //
 cmd ::= createkw(S) uniqueflag(U) INDEX ifnotexists(NE) nm(X) dbnm(D)
-        ON nm(Y) LP idxlist(Z) RP(E). {
+        ON nm(Y) LP idxlist(Z) RP(E) where_opt(W). {
   sqlite3CreateIndex(pParse, &X, &D, 
                      sqlite3SrcListAppend(pParse->db,0,&Y,0), Z, U,
-                      &S, &E, SQLITE_SO_ASC, NE);
+                      &S, &E, W, SQLITE_SO_ASC, NE);
 }
 
 %type uniqueflag {int}

src/sqliteInt.h

@@ -1538,6 +1538,7 @@ struct Index {
   Schema *pSchema;         /* Schema containing this index */
   u8 *aSortOrder;          /* for each column: True==DESC, False==ASC */
   char **azColl;           /* Array of collation sequence names for index */
+  Expr *pPartIdxWhere;     /* WHERE clause for partial indices */
   int tnum;                /* DB Page containing root of this index */
   u16 nColumn;             /* Number of columns in table used by this index */
   u8 onError;              /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
@@ -2783,7 +2784,7 @@ void sqlite3SrcListAssignCursors(Parse*, SrcList*);
 void sqlite3IdListDelete(sqlite3*, IdList*);
 void sqlite3SrcListDelete(sqlite3*, SrcList*);
 Index *sqlite3CreateIndex(Parse*,Token*,Token*,SrcList*,ExprList*,int,Token*,
-                        Token*, int, int);
+                        Token*, Expr*, int, int);
 void sqlite3DropIndex(Parse*, SrcList*, int);
 int sqlite3Select(Parse*, Select*, SelectDest*);
 Select *sqlite3SelectNew(Parse*,ExprList*,SrcList*,Expr*,ExprList*,

test/index6.test

@@ -0,0 +1,33 @@
+# 2013-07-31
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+#
+# Test cases for partial indices
+#
+
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+load_static_extension db wholenumber;
+do_test index6-1.1 {
+  execsql {
+    CREATE TABLE t1(a,b);
+    CREATE INDEX t1a ON t1(a) WHERE a IS NOT NULL;
+    CREATE INDEX t1b ON t1(b) WHERE b>10;
+    CREATE VIRTUAL TABLE nums USING wholenumber;
+    INSERT INTO t1(a,b)
+       SELECT CASE WHEN value%3!=0 THEN value END, value
+         FROM nums WHERE value<=20;
+    SELECT count(a), count(b) FROM t1;
+  }
+} {14 20}
+
+finish_test