Index: src/analyze.c
==================================================================
--- src/analyze.c
+++ src/analyze.c
@@ -32,11 +32,12 @@
 */
 static void openStatTable(
   Parse *pParse,          /* Parsing context */
   int iDb,                /* The database we are looking in */
   int iStatCur,           /* Open the sqlite_stat1 table on this cursor */
-  const char *zWhere      /* Delete entries associated with this table */
+  const char *zWhere,     /* Delete entries for this table or index */
+  const char *zWhereType  /* Either "tbl" or "idx" */
 ){
   static const struct {
     const char *zName;
     const char *zCols;
   } aTable[] = {
@@ -77,11 +78,11 @@
       ** entire contents of the table. */
       aRoot[i] = pStat->tnum;
       sqlite3TableLock(pParse, iDb, aRoot[i], 1, zTab);
       if( zWhere ){
         sqlite3NestedParse(pParse,
-           "DELETE FROM %Q.%s WHERE tbl=%Q", pDb->zName, zTab, zWhere
+           "DELETE FROM %Q.%s WHERE %s=%Q", pDb->zName, zTab, zWhereType, zWhere
         );
       }else{
         /* The sqlite_stat[12] table already exists.  Delete all rows. */
         sqlite3VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
       }
@@ -101,10 +102,11 @@
 ** a single table.
 */
 static void analyzeOneTable(
   Parse *pParse,   /* Parser context */
   Table *pTab,     /* Table whose indices are to be analyzed */
+  Index *pOnlyIdx, /* If not NULL, only analyze this one index */
   int iStatCur,    /* Index of VdbeCursor that writes the sqlite_stat1 table */
   int iMem         /* Available memory locations begin here */
 ){
   sqlite3 *db = pParse->db;    /* Database handle */
   Index *pIdx;                 /* An index to being analyzed */
@@ -158,13 +160,16 @@
   sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
 
   iIdxCur = pParse->nTab++;
   sqlite3VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
   for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
-    int nCol = pIdx->nColumn;
-    KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
+    int nCol;
+    KeyInfo *pKey;
 
+    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
+    nCol = pIdx->nColumn;
+    pKey = sqlite3IndexKeyinfo(pParse, pIdx);
     if( iMem+1+(nCol*2)>pParse->nMem ){
       pParse->nMem = iMem+1+(nCol*2);
     }
 
     /* Open a cursor to the index to be analyzed. */
@@ -381,35 +386,40 @@
   int iMem;
 
   sqlite3BeginWriteOperation(pParse, 0, iDb);
   iStatCur = pParse->nTab;
   pParse->nTab += 2;
-  openStatTable(pParse, iDb, iStatCur, 0);
+  openStatTable(pParse, iDb, iStatCur, 0, 0);
   iMem = pParse->nMem+1;
   for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
     Table *pTab = (Table*)sqliteHashData(k);
-    analyzeOneTable(pParse, pTab, iStatCur, iMem);
+    analyzeOneTable(pParse, pTab, 0, iStatCur, iMem);
   }
   loadAnalysis(pParse, iDb);
 }
 
 /*
 ** Generate code that will do an analysis of a single table in
-** a database.
+** a database.  If pOnlyIdx is not NULL then it is a single index
+** in pTab that should be analyzed.
 */
-static void analyzeTable(Parse *pParse, Table *pTab){
+static void analyzeTable(Parse *pParse, Table *pTab, Index *pOnlyIdx){
   int iDb;
   int iStatCur;
 
   assert( pTab!=0 );
   assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
   iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
   sqlite3BeginWriteOperation(pParse, 0, iDb);
   iStatCur = pParse->nTab;
   pParse->nTab += 2;
-  openStatTable(pParse, iDb, iStatCur, pTab->zName);
-  analyzeOneTable(pParse, pTab, iStatCur, pParse->nMem+1);
+  if( pOnlyIdx ){
+    openStatTable(pParse, iDb, iStatCur, pOnlyIdx->zName, "idx");
+  }else{
+    openStatTable(pParse, iDb, iStatCur, pTab->zName, "tbl");
+  }
+  analyzeOneTable(pParse, pTab, pOnlyIdx, iStatCur, pParse->nMem+1);
   loadAnalysis(pParse, iDb);
 }
 
 /*
 ** Generate code for the ANALYZE command.  The parser calls this routine
@@ -427,10 +437,11 @@
   sqlite3 *db = pParse->db;
   int iDb;
   int i;
   char *z, *zDb;
   Table *pTab;
+  Index *pIdx;
   Token *pTableName;
 
   /* Read the database schema. If an error occurs, leave an error message
   ** and code in pParse and return NULL. */
   assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
@@ -451,29 +462,31 @@
     if( iDb>=0 ){
       analyzeDatabase(pParse, iDb);
     }else{
       z = sqlite3NameFromToken(db, pName1);
       if( z ){
-        pTab = sqlite3LocateTable(pParse, 0, z, 0);
-        sqlite3DbFree(db, z);
-        if( pTab ){
-          analyzeTable(pParse, pTab);
+        if( (pIdx = sqlite3FindIndex(db, z, 0))!=0 ){
+          analyzeTable(pParse, pIdx->pTable, pIdx);
+        }else if( (pTab = sqlite3LocateTable(pParse, 0, z, 0))!=0 ){
+          analyzeTable(pParse, pTab, 0);
         }
+        sqlite3DbFree(db, z);
       }
     }
   }else{
     /* Form 3: Analyze the fully qualified table name */
     iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName);
     if( iDb>=0 ){
       zDb = db->aDb[iDb].zName;
       z = sqlite3NameFromToken(db, pTableName);
       if( z ){
-        pTab = sqlite3LocateTable(pParse, 0, z, zDb);
-        sqlite3DbFree(db, z);
-        if( pTab ){
-          analyzeTable(pParse, pTab);
+        if( (pIdx = sqlite3FindIndex(db, z, zDb))!=0 ){
+          analyzeTable(pParse, pIdx->pTable, pIdx);
+        }else if( (pTab = sqlite3LocateTable(pParse, 0, z, zDb))!=0 ){
+          analyzeTable(pParse, pTab, 0);
         }
+        sqlite3DbFree(db, z);
       }
     }   
   }
 }
 

ADDED   test/analyze7.test
Index: test/analyze7.test
==================================================================
--- /dev/null
+++ test/analyze7.test
@@ -0,0 +1,106 @@
+# 2011 April 1
+#
+# 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.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.
+# This file implements tests for the ANALYZE command when an idnex
+# name is given as the argument.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+# There is nothing to test if ANALYZE is disable for this build.
+#
+ifcapable {!analyze} {
+  finish_test
+  return
+}
+
+# Generate some test data
+#
+do_test analyze7-1.0 {
+  execsql {
+    CREATE TABLE sequence(x INTEGER PRIMARY KEY);
+    INSERT INTO sequence VALUES(1);
+    INSERT INTO sequence VALUES(2);
+    INSERT INTO sequence SELECT x+2 FROM sequence;
+    INSERT INTO sequence SELECT x+4 FROM sequence;
+    INSERT INTO sequence SELECT x+8 FROM sequence;
+    INSERT INTO sequence SELECT x+16 FROM sequence;
+    INSERT INTO sequence SELECT x+32 FROM sequence;
+    INSERT INTO sequence SELECT x+64 FROM sequence;
+    INSERT INTO sequence SELECT x+128 FROM sequence;
+    INSERT INTO sequence SELECT x+256 FROM sequence;
+    CREATE TABLE t1(a,b,c,d);
+    CREATE INDEX t1a ON t1(a);
+    CREATE INDEX t1b ON t1(b);
+    CREATE INDEX t1cd ON t1(c,d);
+    INSERT INTO t1 SELECT x, x, x/100, x FROM sequence;
+    EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123;
+  }
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~10 rows)}}
+do_test analyze7-1.1 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE b=123;}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1b (b=?) (~10 rows)}}
+do_test analyze7-1.2 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=2;}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1cd (c=?) (~10 rows)}}
+
+# Run an analyze on one of the three indices.  Verify that this
+# effects the row-count estimate on the one query that uses that
+# one index.
+#
+do_test analyze7-2.0 {
+  execsql {ANALYZE t1a;}
+  db cache flush
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123;}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
+do_test analyze7-2.1 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE b=123;}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1b (b=?) (~10 rows)}}
+do_test analyze7-2.2 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=2;}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1cd (c=?) (~10 rows)}}
+
+# Verify that since the query planner now things that t1a is more
+# selective than t1b, it prefers to use t1a.
+#
+do_test analyze7-2.3 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123 AND b=123}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
+
+# Run an analysis on another of the three indices.  Verify  that this
+# new analysis works and does not disrupt the previous analysis.
+#
+do_test analyze7-3.0 {
+  execsql {ANALYZE t1cd;}
+  db cache flush;
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123;}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
+do_test analyze7-3.1 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE b=123;}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1b (b=?) (~10 rows)}}
+do_test analyze7-3.2 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=2;}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1cd (c=?) (~102 rows)}}
+do_test analyze7-3.3 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123 AND b=123}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
+do_test analyze7-3.4 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=123 AND b=123}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1b (b=?) (~2 rows)}}
+do_test analyze7-3.5 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123 AND c=123}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
+do_test analyze7-3.6 {
+  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=123 AND d=123 AND b=123}
+} {0 0 0 {SEARCH TABLE t1 USING INDEX t1cd (c=? AND d=?) (~1 rows)}}
+
+finish_test