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

Example 1 with SqlShowTables

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

the class ShowTablesHandler method rewrite.

/** Rewrite the parse tree as SELECT ... FROM INFORMATION_SCHEMA.`TABLES` ... */
@Override
public SqlNode rewrite(SqlNode sqlNode) throws RelConversionException, ForemanSetupException {
    SqlShowTables node = unwrap(sqlNode, SqlShowTables.class);
    List<SqlNode> selectList = Lists.newArrayList();
    SqlNode fromClause;
    SqlNode where;
    // create select columns
    selectList.add(new SqlIdentifier(SHRD_COL_TABLE_SCHEMA, SqlParserPos.ZERO));
    selectList.add(new SqlIdentifier(SHRD_COL_TABLE_NAME, SqlParserPos.ZERO));
    fromClause = new SqlIdentifier(ImmutableList.of(IS_SCHEMA_NAME, TAB_TABLES), SqlParserPos.ZERO);
    final SqlIdentifier db = node.getDb();
    String tableSchema;
    if (db != null) {
        tableSchema = db.toString();
    } else {
        // If no schema is given in SHOW TABLES command, list tables from current schema
        SchemaPlus schema = config.getConverter().getDefaultSchema();
        if (SchemaUtilites.isRootSchema(schema)) {
            // If the default schema is a root schema, throw an error to select a default schema
            throw UserException.validationError().message("No default schema selected. Select a schema using 'USE schema' command").build(logger);
        }
        final AbstractSchema drillSchema = SchemaUtilites.unwrapAsDrillSchemaInstance(schema);
        tableSchema = drillSchema.getFullSchemaName();
    }
    final String charset = Util.getDefaultCharset().name();
    where = DrillParserUtil.createCondition(new SqlIdentifier(SHRD_COL_TABLE_SCHEMA, SqlParserPos.ZERO), SqlStdOperatorTable.EQUALS, SqlLiteral.createCharString(tableSchema, charset, SqlParserPos.ZERO));
    SqlNode filter = null;
    final SqlNode likePattern = node.getLikePattern();
    if (likePattern != null) {
        filter = DrillParserUtil.createCondition(new SqlIdentifier(SHRD_COL_TABLE_NAME, SqlParserPos.ZERO), SqlStdOperatorTable.LIKE, likePattern);
    } else if (node.getWhereClause() != null) {
        filter = node.getWhereClause();
    }
    where = DrillParserUtil.createCondition(where, SqlStdOperatorTable.AND, filter);
    return new SqlSelect(SqlParserPos.ZERO, null, new SqlNodeList(selectList, SqlParserPos.ZERO), fromClause, where, null, null, null, null, null, null);
}