Examples with SqlDescribeTable org.apache.drill.exec.planner.sql.parser.SqlDescribeTable used on opensource projects

Example 1 with SqlDescribeTable

use of org.apache.drill.exec.planner.sql.parser.SqlDescribeTable in project drill by apache.

the class DescribeTableHandler method rewrite.

/** Rewrite the parse tree as SELECT ... FROM INFORMATION_SCHEMA.COLUMNS ... */
@Override
public SqlNode rewrite(SqlNode sqlNode) throws RelConversionException, ForemanSetupException {
    SqlDescribeTable node = unwrap(sqlNode, SqlDescribeTable.class);
    try {
        List<SqlNode> selectList = ImmutableList.of((SqlNode) new SqlIdentifier(COLS_COL_COLUMN_NAME, SqlParserPos.ZERO), new SqlIdentifier(COLS_COL_DATA_TYPE, SqlParserPos.ZERO), new SqlIdentifier(COLS_COL_IS_NULLABLE, SqlParserPos.ZERO));
        SqlNode fromClause = new SqlIdentifier(ImmutableList.of(IS_SCHEMA_NAME, TAB_COLUMNS), null, SqlParserPos.ZERO, null);
        final SqlIdentifier table = node.getTable();
        final SchemaPlus defaultSchema = config.getConverter().getDefaultSchema();
        final List<String> schemaPathGivenInCmd = Util.skipLast(table.names);
        final SchemaPlus schema = SchemaUtilites.findSchema(defaultSchema, schemaPathGivenInCmd);
        final String charset = Util.getDefaultCharset().name();
        if (schema == null) {
            SchemaUtilites.throwSchemaNotFoundException(defaultSchema, SchemaUtilites.SCHEMA_PATH_JOINER.join(schemaPathGivenInCmd));
        }
        if (SchemaUtilites.isRootSchema(schema)) {
            throw UserException.validationError().message("No schema selected.").build(logger);
        }
        final String tableName = Util.last(table.names);
        // find resolved schema path
        final String schemaPath = SchemaUtilites.unwrapAsDrillSchemaInstance(schema).getFullSchemaName();
        if (schema.getTable(tableName) == null) {
            throw UserException.validationError().message("Unknown table [%s] in schema [%s]", tableName, schemaPath).build(logger);
        }
        SqlNode schemaCondition = null;
        if (!SchemaUtilites.isRootSchema(schema)) {
            schemaCondition = DrillParserUtil.createCondition(new SqlIdentifier(SHRD_COL_TABLE_SCHEMA, SqlParserPos.ZERO), SqlStdOperatorTable.EQUALS, SqlLiteral.createCharString(schemaPath, charset, SqlParserPos.ZERO));
        }
        SqlNode where = DrillParserUtil.createCondition(new SqlIdentifier(SHRD_COL_TABLE_NAME, SqlParserPos.ZERO), SqlStdOperatorTable.EQUALS, SqlLiteral.createCharString(tableName, charset, SqlParserPos.ZERO));
        where = DrillParserUtil.createCondition(schemaCondition, SqlStdOperatorTable.AND, where);
        SqlNode columnFilter = null;
        if (node.getColumn() != null) {
            columnFilter = DrillParserUtil.createCondition(new SqlIdentifier(COLS_COL_COLUMN_NAME, SqlParserPos.ZERO), SqlStdOperatorTable.EQUALS, SqlLiteral.createCharString(node.getColumn().toString(), charset, SqlParserPos.ZERO));
        } else if (node.getColumnQualifier() != null) {
            columnFilter = DrillParserUtil.createCondition(new SqlIdentifier(COLS_COL_COLUMN_NAME, SqlParserPos.ZERO), SqlStdOperatorTable.LIKE, node.getColumnQualifier());
        }
        where = DrillParserUtil.createCondition(where, SqlStdOperatorTable.AND, columnFilter);
        return new SqlSelect(SqlParserPos.ZERO, null, new SqlNodeList(selectList, SqlParserPos.ZERO), fromClause, where, null, null, null, null, null, null);
    } catch (Exception ex) {
        throw UserException.planError(ex).message("Error while rewriting DESCRIBE query: %d", ex.getMessage()).build(logger);
    }
}