Examples with SqlMerge org.apache.calcite.sql.SqlMerge used on opensource projects

Example 6 with SqlMerge

use of org.apache.calcite.sql.SqlMerge in project calcite by apache.

the class SqlValidatorImpl method rewriteUpdateToMerge.

private SqlNode rewriteUpdateToMerge(SqlUpdate updateCall, SqlNode selfJoinSrcExpr) {
    // Make sure target has an alias.
    if (updateCall.getAlias() == null) {
        updateCall.setAlias(new SqlIdentifier(UPDATE_TGT_ALIAS, SqlParserPos.ZERO));
    }
    SqlNode selfJoinTgtExpr = getSelfJoinExprForUpdate(updateCall.getTargetTable(), updateCall.getAlias().getSimple());
    assert selfJoinTgtExpr != null;
    // Create join condition between source and target exprs,
    // creating a conjunction with the user-level WHERE
    // clause if one was supplied
    SqlNode condition = updateCall.getCondition();
    SqlNode selfJoinCond = SqlStdOperatorTable.EQUALS.createCall(SqlParserPos.ZERO, selfJoinSrcExpr, selfJoinTgtExpr);
    if (condition == null) {
        condition = selfJoinCond;
    } else {
        condition = SqlStdOperatorTable.AND.createCall(SqlParserPos.ZERO, selfJoinCond, condition);
    }
    SqlNode target = updateCall.getTargetTable().clone(SqlParserPos.ZERO);
    // For the source, we need to anonymize the fields, so
    // that for a statement like UPDATE T SET I = I + 1,
    // there's no ambiguity for the "I" in "I + 1";
    // this is OK because the source and target have
    // identical values due to the self-join.
    // Note that we anonymize the source rather than the
    // target because downstream, the optimizer rules
    // don't want to see any projection on top of the target.
    IdentifierNamespace ns = new IdentifierNamespace(this, target, null, null);
    RelDataType rowType = ns.getRowType();
    SqlNode source = updateCall.getTargetTable().clone(SqlParserPos.ZERO);
    final SqlNodeList selectList = new SqlNodeList(SqlParserPos.ZERO);
    int i = 1;
    for (RelDataTypeField field : rowType.getFieldList()) {
        SqlIdentifier col = new SqlIdentifier(field.getName(), SqlParserPos.ZERO);
        selectList.add(SqlValidatorUtil.addAlias(col, UPDATE_ANON_PREFIX + i));
        ++i;
    }
    source = new SqlSelect(SqlParserPos.ZERO, null, selectList, source, null, null, null, null, null, null, null);
    source = SqlValidatorUtil.addAlias(source, UPDATE_SRC_ALIAS);
    SqlMerge mergeCall = new SqlMerge(updateCall.getParserPosition(), target, condition, source, updateCall, null, null, updateCall.getAlias());
    rewriteMerge(mergeCall);
    return mergeCall;
}