/**
* Position our index scan to 'ourIndexRow'.
*
* <p>This creates the scan the first time it is called.
*
* @exception StandardException Thrown on error
*/
private void setScan() throws StandardException {
/*
* -sf- Derby makes an assumption about system tables that isn't true
* for Splice land, which results in WriteConflicts occurring
* when you try to drop tables
*
* With indices, Derby only ever creates start and stop keys for the scan.
* However, if the entire index is to be scanned, one or more column in the start/stop
* key may be null. With db this was apparently treated acceptably, but in Splice
* this results in garbage start and stop row keys, which in turn results in deleting
* every row in the index instead of deleting just the rows of interest.
*
* Thus, the following hack. When the row is not entirely filled, we convert
* the start/stop key into a single ANDed equals qualifier[], and use that instead
*/
DataValueDescriptor[] ourRowDvds = ourIndexRow.getRowArray();
int numNonNull = ourRowDvds.length;
for (int i = 0; i < ourRowDvds.length; i++) {
if (ourRowDvds[i].isNull()) {
numNonNull--;
}
}
Qualifier[][] qualifiers = null;
if (numNonNull < ourRowDvds.length) {
qualifiers = new Qualifier[1][];
qualifiers[0] = new Qualifier[numNonNull];
for (int dvdPos = 0, qualPos = 0; dvdPos < ourRowDvds.length; dvdPos++) {
if (ourRowDvds[dvdPos].isNull()) continue;
ScanQualifier qualifier = new GenericScanQualifier();
qualifier.setQualifier(
dvdPos, ourRowDvds[dvdPos], DataValueDescriptor.ORDER_OP_EQUALS, false, false, false);
qualifiers[0][qualPos] = qualifier;
}
}
/* Get the SC from the activation if re-using */
if (!ownIndexSC) {
indexSC = activation.getIndexScanController();
} else if (indexSC == null) {
RowLocation templateBaseRowLocation = baseCC.newRowLocationTemplate();
/* DataDictionary doesn't have compiled info */
if (indexSCOCI == null) {
indexSC =
tc.openScan(
indexCID,
false, /* hold */
TransactionController.OPENMODE_FORUPDATE, /* forUpdate */
lockMode,
isolationLevel,
(FormatableBitSet) null, /* all fields */
ourIndexRow.getRowArray(), /* startKeyValue */
ScanController.GE, /* startSearchOp */
qualifiers, /* qualifier */
ourIndexRow.getRowArray(), /* stopKeyValue */
ScanController.GT /* stopSearchOp */);
} else {
indexSC =
tc.openCompiledScan(
false, /* hold */
TransactionController.OPENMODE_FORUPDATE, /* forUpdate */
lockMode,
isolationLevel,
(FormatableBitSet) null, /* all fields */
ourIndexRow.getRowArray(), /* startKeyValue */
ScanController.GE, /* startSearchOp */
qualifiers, /* qualifier */
ourIndexRow.getRowArray(), /* stopKeyValue */
ScanController.GT, /* stopSearchOp */
indexSCOCI,
indexDCOCI);
}
} else {
indexSC.reopenScan(
ourIndexRow.getRowArray(), /* startKeyValue */
ScanController.GE, /* startSearchOperator */
qualifiers, /* qualifier */
ourIndexRow.getRowArray(), /* stopKeyValue */
ScanController.GT /* stopSearchOperator */);
}
}
