static int tclvarBestIndex(sqlite3_vtab tab, ref sqlite3_index_info pIdxInfo)
{
int ii;
for (ii = 0; ii < pIdxInfo.nConstraint; ii++)
{
sqlite3_index_constraint pCons = pIdxInfo.aConstraint[ii];
if (pCons.iColumn == 0 && pCons.usable &&
pCons.op == SQLITE_INDEX_CONSTRAINT_EQ)
{
sqlite3_index_constraint_usage pUsage = new sqlite3_index_constraint_usage();
pUsage = pIdxInfo.aConstraintUsage[ii];
pUsage.omit = false;
pUsage.argvIndex = 1;
return(SQLITE_OK);
}
}
for (ii = 0; ii < pIdxInfo.nConstraint; ii++)
{
sqlite3_index_constraint pCons = pIdxInfo.aConstraint[ii];
if (pCons.iColumn == 0 && pCons.usable &&
pCons.op == SQLITE_INDEX_CONSTRAINT_MATCH)
{
sqlite3_index_constraint_usage pUsage = new sqlite3_index_constraint_usage();
pUsage = pIdxInfo.aConstraintUsage[ii];
pUsage.omit = true;
pUsage.argvIndex = 1;
return(SQLITE_OK);
}
}
return(SQLITE_OK);
}
/*
** The echo module implements the subset of query constraints and sort
** orders that may take advantage of SQLite indices on the underlying
** real table. For example, if the real table is declared as:
**
** CREATE TABLE real(a, b, c);
** CREATE INDEX real_index ON real(b);
**
** then the echo module handles WHERE or ORDER BY clauses that refer
** to the column "b", but not "a" or "c". If a multi-column index is
** present, only its left most column is considered.
**
** This xBestIndex method encodes the proposed search strategy as
** an SQL query on the real table underlying the virtual echo module
** table and stores the query in sqlite3_index_info.idxStr. The SQL
** statement is of the form:
**
** SELECT rowid, * FROM <real-table> ?<where-clause>? ?<order-by-clause>?
**
** where the <where-clause> and <order-by-clause> are determined
** by the contents of the structure pointed to by the pIdxInfo argument.
*/
static int echoBestIndex( sqlite3_vtab vtab, ref sqlite3_index_info pIdxInfo )
{
int ii;
string zQuery = "";
string zNew;
int nArg = 0;
string zSep = "WHERE";
echo_vtab pVtab = (echo_vtab)vtab;
sqlite3_stmt pStmt = null;
Tcl_Interp interp = pVtab.interp;
int nRow = 0;
int useIdx = 0;
int rc = SQLITE_OK;
int useCost = 0;
double cost = 0;
int isIgnoreUsable = 0;
if ( TCL.Tcl_GetVar( interp, "echo_module_ignore_usable", (TCL.VarFlag)TCL.TCL_GLOBAL_ONLY ).ToString() != "" )
{
isIgnoreUsable = 1;
}
if ( simulateVtabError( pVtab, "xBestIndex" ) != 0 )
{
return SQLITE_ERROR;
}
/* Determine the number of rows in the table and store this value in local
** variable nRow. The 'estimated-cost' of the scan will be the number of
** rows in the table for a linear scan, or the log (base 2) of the
** number of rows if the proposed scan uses an index.
*/
if ( TCL.Tcl_GetVar( interp, "echo_module_cost", (TCL.VarFlag)TCL.TCL_GLOBAL_ONLY ).ToString() != "" )
{
Double.TryParse( TCL.Tcl_GetVar( interp, "echo_module_cost", (TCL.VarFlag)TCL.TCL_GLOBAL_ONLY ).ToString(), out cost );
useCost = 1;
}
else
{
zQuery = sqlite3_mprintf( "SELECT count() FROM %Q", pVtab.zTableName );
//if ( null == zQuery )
//{
// return SQLITE_NOMEM;
//}
rc = sqlite3_prepare( pVtab.db, zQuery, -1, ref pStmt, 0 );
//sqlite3_free(zQuery);
if ( rc != SQLITE_OK )
{
return rc;
}
sqlite3_step( pStmt );
nRow = sqlite3_column_int( pStmt, 0 );
rc = sqlite3_finalize( pStmt );
if ( rc != SQLITE_OK )
{
return rc;
}
}
zQuery = sqlite3_mprintf( "SELECT rowid, * FROM %Q", pVtab.zTableName );
//if ( null == zQuery )
//{
// return SQLITE_NOMEM;
//}
for ( ii = 0; ii < pIdxInfo.nConstraint; ii++ )
{
sqlite3_index_constraint pConstraint;
sqlite3_index_constraint_usage pUsage;
int iCol;
pConstraint = pIdxInfo.aConstraint[ii];
pUsage = pIdxInfo.aConstraintUsage[ii];
if ( 0 == isIgnoreUsable && !pConstraint.usable )
continue;
iCol = pConstraint.iColumn;
if ( iCol < 0 || pVtab.aIndex[iCol] != 0 )
{
string zCol;
string zOp = "";
useIdx = 1;
if ( iCol >= 0 )
{
zCol = pVtab.aCol[iCol];
}
else
{
zCol = "rowid";
}
switch ( pConstraint.op )
{
case SQLITE_INDEX_CONSTRAINT_EQ:
zOp = "=";
break;
case SQLITE_INDEX_CONSTRAINT_LT:
zOp = "<";
break;
case SQLITE_INDEX_CONSTRAINT_GT:
zOp = ">";
break;
case SQLITE_INDEX_CONSTRAINT_LE:
zOp = "<=";
break;
case SQLITE_INDEX_CONSTRAINT_GE:
zOp = ">=";
break;
case SQLITE_INDEX_CONSTRAINT_MATCH:
zOp = "LIKE";
break;
}
if ( zOp[0] == 'L' )
{
zNew = sqlite3_mprintf( " %s %s LIKE (SELECT '%%'||?||'%%')",
zSep, zCol );
}
else
{
zNew = sqlite3_mprintf( " %s %s %s ?", zSep, zCol, zOp );
}
string_concat( ref zQuery, zNew, 1, ref rc );
zSep = "AND";
pUsage.argvIndex = ++nArg;
pUsage.omit = true;
}
}
/* If there is only one term in the ORDER BY clause, and it is
** on a column that this virtual table has an index for, then consume
** the ORDER BY clause.
*/
if ( pIdxInfo.nOrderBy == 1 && ( pIdxInfo.aOrderBy[0].iColumn < 0 || pVtab.aIndex[pIdxInfo.aOrderBy[0].iColumn] != 0 ) )
{
int iCol = pIdxInfo.aOrderBy[0].iColumn;
string zCol;
string zDir = pIdxInfo.aOrderBy[0].desc ? "DESC" : "ASC";
if ( iCol >= 0 )
{
zCol = pVtab.aCol[iCol];
}
else
{
zCol = "rowid";
}
zNew = sqlite3_mprintf( " ORDER BY %s %s", zCol, zDir );
string_concat( ref zQuery, zNew, 1, ref rc );
pIdxInfo.orderByConsumed = true;
}
appendToEchoModule( pVtab.interp, "xBestIndex" );
;
appendToEchoModule( pVtab.interp, zQuery );
if ( null == zQuery )
{
return rc;
}
pIdxInfo.idxNum = hashString( zQuery );
pIdxInfo.idxStr = zQuery;
pIdxInfo.needToFreeIdxStr = 1;
if ( useCost != 0 )
{
pIdxInfo.estimatedCost = cost;
}
else if ( useIdx != 0 )
{
/* Approximation of log2(nRow). */
for ( ii = 0; ii < ( sizeof( int ) * 8 ); ii++ )
{
if ( ( nRow & ( 1 << ii ) ) != 0 )
{
pIdxInfo.estimatedCost = (double)ii;
}
}
}
else
{
pIdxInfo.estimatedCost = (double)nRow;
}
return rc;
}
/*
** Analyse the WHERE condition.
*/
static int intarrayBestIndex( sqlite3_vtab tab, ref sqlite3_index_info pIdxInfo )
{
return SQLITE_OK;
}
/*
** Analyse the WHERE condition.
*/
static int schemaBestIndex(sqlite3_vtab tab, ref sqlite3_index_info pIdxInfo)
{
return(SQLITE_OK);
}
static int tclvarBestIndex( sqlite3_vtab tab, ref sqlite3_index_info pIdxInfo )
{
int ii;
for(ii=0; ii<pIdxInfo.nConstraint; ii++){
sqlite3_index_constraint pCons = pIdxInfo.aConstraint[ii];
if( pCons.iColumn==0 && pCons.usable
&& pCons.op==SQLITE_INDEX_CONSTRAINT_EQ ){
sqlite3_index_constraint_usage pUsage = new sqlite3_index_constraint_usage();
pUsage = pIdxInfo.aConstraintUsage[ii];
pUsage.omit = false;
pUsage.argvIndex = 1;
return SQLITE_OK;
}
}
for(ii=0; ii<pIdxInfo.nConstraint; ii++){
sqlite3_index_constraint pCons = pIdxInfo.aConstraint[ii];
if( pCons.iColumn==0 && pCons.usable
&& pCons.op==SQLITE_INDEX_CONSTRAINT_MATCH ){
sqlite3_index_constraint_usage pUsage = new sqlite3_index_constraint_usage();
pUsage = pIdxInfo.aConstraintUsage[ii];
pUsage.omit = true;
pUsage.argvIndex = 1;
return SQLITE_OK;
}
}
return SQLITE_OK;
}
/*
** Search for terms of these forms:
**
** (1) value > $value
** (2) value >= $value
** (4) value < $value
** (8) value <= $value
**
** idxNum is an ORed combination of 1 or 2 with 4 or 8.
*/
static int wholenumberBestIndex(
sqlite3_vtab vtab,
ref sqlite3_index_info pIdxInfo
)
{
int i;
int idxNum = 0;
int argvIdx = 1;
int ltIdx = -1;
int gtIdx = -1;
sqlite3_index_constraint pConstraint;
//pConstraint = pIdxInfo.aConstraint;
for ( i = 0; i < pIdxInfo.nConstraint; i++ )//, pConstraint++)
{
pConstraint = pIdxInfo.aConstraint[i];
if ( pConstraint.usable == false )
continue;
if ( ( idxNum & 3 ) == 0 && pConstraint.op == SQLITE_INDEX_CONSTRAINT_GT )
{
idxNum |= 1;
ltIdx = i;
}
if ( ( idxNum & 3 ) == 0 && pConstraint.op == SQLITE_INDEX_CONSTRAINT_GE )
{
idxNum |= 2;
ltIdx = i;
}
if ( ( idxNum & 12 ) == 0 && pConstraint.op == SQLITE_INDEX_CONSTRAINT_LT )
{
idxNum |= 4;
gtIdx = i;
}
if ( ( idxNum & 12 ) == 0 && pConstraint.op == SQLITE_INDEX_CONSTRAINT_LE )
{
idxNum |= 8;
gtIdx = i;
}
}
pIdxInfo.idxNum = idxNum;
if ( ltIdx >= 0 )
{
pIdxInfo.aConstraintUsage[ltIdx].argvIndex = argvIdx++;
pIdxInfo.aConstraintUsage[ltIdx].omit = true;
}
if ( gtIdx >= 0 )
{
pIdxInfo.aConstraintUsage[gtIdx].argvIndex = argvIdx;
pIdxInfo.aConstraintUsage[gtIdx].omit = true;
}
if ( pIdxInfo.nOrderBy == 1
&& pIdxInfo.aOrderBy[0].desc == false
)
{
pIdxInfo.orderByConsumed = true;
}
pIdxInfo.estimatedCost = (double)1;
return SQLITE_OK;
}
/*
** Search for terms of these forms:
**
** (1) value > $value
** (2) value >= $value
** (4) value < $value
** (8) value <= $value
**
** idxNum is an ORed combination of 1 or 2 with 4 or 8.
*/
static int wholenumberBestIndex(
sqlite3_vtab vtab,
ref sqlite3_index_info pIdxInfo
)
{
int i;
int idxNum = 0;
int argvIdx = 1;
int ltIdx = -1;
int gtIdx = -1;
sqlite3_index_constraint pConstraint;
//pConstraint = pIdxInfo.aConstraint;
for (i = 0; i < pIdxInfo.nConstraint; i++)//, pConstraint++)
{
pConstraint = pIdxInfo.aConstraint[i];
if (pConstraint.usable == false)
{
continue;
}
if ((idxNum & 3) == 0 && pConstraint.op == SQLITE_INDEX_CONSTRAINT_GT)
{
idxNum |= 1;
ltIdx = i;
}
if ((idxNum & 3) == 0 && pConstraint.op == SQLITE_INDEX_CONSTRAINT_GE)
{
idxNum |= 2;
ltIdx = i;
}
if ((idxNum & 12) == 0 && pConstraint.op == SQLITE_INDEX_CONSTRAINT_LT)
{
idxNum |= 4;
gtIdx = i;
}
if ((idxNum & 12) == 0 && pConstraint.op == SQLITE_INDEX_CONSTRAINT_LE)
{
idxNum |= 8;
gtIdx = i;
}
}
pIdxInfo.idxNum = idxNum;
if (ltIdx >= 0)
{
pIdxInfo.aConstraintUsage[ltIdx].argvIndex = argvIdx++;
pIdxInfo.aConstraintUsage[ltIdx].omit = true;
}
if (gtIdx >= 0)
{
pIdxInfo.aConstraintUsage[gtIdx].argvIndex = argvIdx;
pIdxInfo.aConstraintUsage[gtIdx].omit = true;
}
if (pIdxInfo.nOrderBy == 1 &&
pIdxInfo.aOrderBy[0].desc == false
)
{
pIdxInfo.orderByConsumed = true;
}
pIdxInfo.estimatedCost = (double)1;
return(SQLITE_OK);
}
/*
** There is no "best-index". This virtual table always does a linear
** scan of the binary VFS log file.
*/
static int statBestIndex( sqlite3_vtab tab, ref sqlite3_index_info pIdxInfo )
{
/* Records are always returned in ascending order of (name, path).
** If this will satisfy the client, set the orderByConsumed flag so that
** SQLite does not do an external sort.
*/
if ( ( pIdxInfo.nOrderBy == 1
&& pIdxInfo.aOrderBy[0].iColumn == 0
&& pIdxInfo.aOrderBy[0].desc == false
) ||
( pIdxInfo.nOrderBy == 2
&& pIdxInfo.aOrderBy[0].iColumn == 0
&& pIdxInfo.aOrderBy[0].desc == false
&& pIdxInfo.aOrderBy[1].iColumn == 1
&& pIdxInfo.aOrderBy[1].desc == false
)
)
{
pIdxInfo.orderByConsumed = true;
}
pIdxInfo.estimatedCost = 10.0;
return SQLITE_OK;
}