Begin a branch that experimentally replaces sqlite_stat2 with a new table

called sqlite_stat3 that will hopefully facilitate better query
planning decisions.

FossilOrigin-Name: 52e1d7e8ddd4bb5ef3a9d00fd2d719a8a784f807

src/sqliteInt.h

@@ -445,6 +445,18 @@ typedef INT8_TYPE i8;              /* 1-byte signed integer */
 */
 #define SQLITE_MAX_U32  ((((u64)1)<<32)-1)
 
+/*
+** The datatype used to store estimates of the number of rows in a
+** table or index.  This is an unsigned integer type.  For 99.9% of
+** the world, a 32-bit integer is sufficient.  But a 64-bit integer
+** can be used at compile-time if desired.
+*/
+#ifdef SQLITE_64BIT_STATS
+ typedef u64 tRowcnt;    /* 64-bit only if requested at compile-time */
+#else
+ typedef u32 tRowcnt;    /* 32-bit is the default */
+#endif
+
 /*
 ** Macros to determine whether the machine is big or little endian,
 ** evaluated at runtime.
@@ -1278,7 +1290,7 @@ struct Table {
   Column *aCol;        /* Information about each column */
   Index *pIndex;       /* List of SQL indexes on this table. */
   int tnum;            /* Root BTree node for this table (see note above) */
-  unsigned nRowEst;    /* Estimated rows in table - from sqlite_stat1 table */
+  tRowcnt nRowEst;     /* Estimated rows in table - from sqlite_stat1 table */
   Select *pSelect;     /* NULL for tables.  Points to definition if a view. */
   u16 nRef;            /* Number of pointers to this Table */
   u8 tabFlags;         /* Mask of TF_* values */
@@ -1477,18 +1489,21 @@ struct Index {
   char *zName;     /* Name of this index */
   int nColumn;     /* Number of columns in the table used by this index */
   int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
-  unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
+  tRowcnt *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
   Table *pTable;   /* The SQL table being indexed */
   int tnum;        /* Page containing root of this index in database file */
   u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
   u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
   u8 bUnordered;   /* Use this index for == or IN queries only */
+  u8 nSample;      /* Number of elements in aSample[] */
   char *zColAff;   /* String defining the affinity of each column */
   Index *pNext;    /* The next index associated with the same table */
   Schema *pSchema; /* Schema containing this index */
   u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
   char **azColl;   /* Array of collation sequence names for index */
-  IndexSample *aSample;    /* Array of SQLITE_INDEX_SAMPLES samples */
+#ifdef SQLITE_ENABLE_STAT3
+  IndexSample *aSample;    /* Samples of the left-most key */
+#endif
 };
 
 /*
@@ -1498,10 +1513,13 @@ struct Index {
 struct IndexSample {
   union {
     char *z;        /* Value if eType is SQLITE_TEXT or SQLITE_BLOB */
-    double r;       /* Value if eType is SQLITE_FLOAT or SQLITE_INTEGER */
+    double r;       /* Value if eType is SQLITE_FLOAT */
+    i64 i;          /* Value if eType is SQLITE_INTEGER */
   } u;
   u8 eType;         /* SQLITE_NULL, SQLITE_INTEGER ... etc. */
-  u8 nByte;         /* Size in byte of text or blob. */
+  u16 nByte;        /* Size in byte of text or blob. */
+  tRowcnt nEq;      /* Est. number of rows where the key equals this sample */
+  tRowcnt nLt;      /* Est. number of rows where key is less than this sample */
 };
 
 /*
@@ -2707,6 +2725,7 @@ void sqlite3CreateView(Parse*,Token*,Token*,Token*,Select*,int,int);
 #endif
 
 void sqlite3DropTable(Parse*, SrcList*, int, int);
+void sqlite3CodeDropTable(Parse*, Table*, int, int);
 void sqlite3DeleteTable(sqlite3*, Table*);
 #ifndef SQLITE_OMIT_AUTOINCREMENT
   void sqlite3AutoincrementBegin(Parse *pParse);
@@ -2963,7 +2982,7 @@ void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8,
 void sqlite3ValueFree(sqlite3_value*);
 sqlite3_value *sqlite3ValueNew(sqlite3 *);
 char *sqlite3Utf16to8(sqlite3 *, const void*, int, u8);
-#ifdef SQLITE_ENABLE_STAT2
+#ifdef SQLITE_ENABLE_STAT3
 char *sqlite3Utf8to16(sqlite3 *, u8, char *, int, int *);
 #endif
 int sqlite3ValueFromExpr(sqlite3 *, Expr *, u8, u8, sqlite3_value **);