SQLite

/*
** Reclaim the memory used by an index
*/
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);
}

/*
** For the index called zIdxName which is found in the database iDb,
** unlike that index from its Table then remove the index from

  }else if( autoInc ){
#ifndef SQLITE_OMIT_AUTOINCREMENT
    sqlite3ErrorMsg(pParse, "AUTOINCREMENT is only allowed on an "
       "INTEGER PRIMARY KEY");
#endif
  }else{
    Index *p;
    p = sqlite3CreateIndex(pParse, 0, 0, 0, pList, onError, 0, 0,
                           0, sortOrder, 0);
    if( p ){
      p->autoIndex = 2;
    }
    pList = 0;
  }

primary_key_exit:

  Token *pName1,     /* First part of index name. May be NULL */
  Token *pName2,     /* Second part of index name. May be NULL */
  SrcList *pTblName, /* Table to index. Use pParse->pNewTable if 0 */
  ExprList *pList,   /* A list of columns to be indexed */
  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 */
){
  Index *pRet = 0;     /* Pointer to return */
  Table *pTab = 0;     /* Table to be indexed */
  Index *pIndex = 0;   /* The index to be created */
  char *zName = 0;     /* Name of the index */

  memcpy(pIndex->zName, zName, nName+1);
  pIndex->pTable = pTab;
  pIndex->nColumn = pList->nExpr;
  pIndex->onError = (u8)onError;
  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
  */
  if( pDb->pSchema->file_format>=4 ){
    sortOrderMask = -1;   /* Honor DESC */
  }else{

    }
    pRet = pIndex;
    pIndex = 0;
  }

  /* Clean up before exiting */
exit_create_index:
  if( pIndex ) freeIndex(db, pIndex);

  sqlite3ExprDelete(db, pPIWhere);

  sqlite3ExprListDelete(db, pList);
  sqlite3SrcListDelete(db, pTblName);
  sqlite3DbFree(db, zName);
  return pRet;
}

/*

// In addition to the type name, we also care about the primary key and
// UNIQUE constraints.
//
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,
                                                     0,0,0,0);}
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);}
ccons ::= defer_subclause(D).    {sqlite3DeferForeignKey(pParse,D);}
ccons ::= COLLATE ids(C).        {sqlite3AddCollateType(pParse, &C);}

// The optional AUTOINCREMENT keyword

conslist ::= tcons.
tconscomma ::= COMMA.            {pParse->constraintName.n = 0;}
tconscomma ::= .
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,0,0,0,0,0);}
tcons ::= CHECK LP expr(E) RP onconf.
                                 {sqlite3AddCheckConstraint(pParse,E.pExpr);}
tcons ::= FOREIGN KEY LP idxlist(FA) RP
          REFERENCES nm(T) idxlist_opt(TA) refargs(R) defer_subclause_opt(D). {
    sqlite3CreateForeignKey(pParse, FA, &T, TA, R);
    sqlite3DeferForeignKey(pParse, D);
}

nexprlist(A) ::= expr(Y).
    {A = sqlite3ExprListAppend(pParse,0,Y.pExpr);}


///////////////////////////// The CREATE INDEX command ///////////////////////
//
cmd ::= createkw(S) uniqueflag(U) INDEX ifnotexists(NE) nm(X) dbnm(D)
        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, W, SQLITE_SO_ASC, NE);
}

%type uniqueflag {int}
uniqueflag(A) ::= UNIQUE.  {A = OE_Abort;}
uniqueflag(A) ::= .        {A = OE_None;}

%type idxlist {ExprList*}

  tRowcnt *aiRowEst;       /* From ANALYZE: Est. rows selected by each column */
  Table *pTable;           /* The SQL table being indexed */
  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;          /* 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 */
  unsigned autoIndex:2;    /* 1==UNIQUE, 2==PRIMARY KEY, 0==CREATE INDEX */
  unsigned bUnordered:1;   /* Use this index for == or IN queries only */
  unsigned uniqNotNull:1;  /* True if UNIQUE and NOT NULL for all columns */
#ifdef SQLITE_ENABLE_STAT3

void sqlite3SrcListIndexedBy(Parse *, SrcList *, Token *);
int sqlite3IndexedByLookup(Parse *, struct SrcList_item *);
void sqlite3SrcListShiftJoinType(SrcList*);
void sqlite3SrcListAssignCursors(Parse*, SrcList*);
void sqlite3IdListDelete(sqlite3*, IdList*);
void sqlite3SrcListDelete(sqlite3*, SrcList*);
Index *sqlite3CreateIndex(Parse*,Token*,Token*,SrcList*,ExprList*,int,Token*,
                        Token*, Expr*, int, int);
void sqlite3DropIndex(Parse*, SrcList*, int);
int sqlite3Select(Parse*, Select*, SelectDest*);
Select *sqlite3SelectNew(Parse*,ExprList*,SrcList*,Expr*,ExprList*,
                         Expr*,ExprList*,u16,Expr*,Expr*);
void sqlite3SelectDelete(sqlite3*, Select*);
Table *sqlite3SrcListLookup(Parse*, SrcList*);
int sqlite3IsReadOnly(Parse*, Table*, int);

# 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