org.apache.hadoop.hive.metastore.tools

Class SQLGenerator

java.lang.Object

org.apache.hadoop.hive.metastore.tools.SQLGenerator

public final class SQLGenerator
extends Object

Helper class that generates SQL queries with syntax specific to target DB todo: why throw MetaException?

Constructor Summary

Constructors

Constructor and Description
SQLGenerator(DatabaseProduct dbProduct, org.apache.hadoop.conf.Configuration conf)

Method Summary

Modifier and Type	Method and Description
String	addEscapeCharacters(String s)
String	addForUpdateClause(String selectStatement) Given a selectStatement, decorated it with FOR UPDATE or semantically equivalent construct.
String	addLimitClause(int numRows, String noSelectsqlQuery) Suppose you have a query "select a,b from T" and you want to limit the result set to the first 5 rows.
List<PreparedStatement>	createInsertValuesPreparedStmt(Connection dbConn, String tblColumns, List<String> rows, List<List<String>> paramsList) Generates "Insert into T(a,b,c) values(1,2,'f'),(3,4,'c')" for appropriate DB
List<String>	createInsertValuesStmt(String tblColumns, List<String> rows) Generates "Insert into T(a,b,c) values(1,2,'f'),(3,4,'c')" for appropriate DB.
String	createTxnLockStatement(boolean shared) Creates a lock statement for open/commit transaction based on the dbProduct in shared read / exclusive mode.
List<String>	getCreateQueriesForMetastoreSummary() Create or replace a view that stores all the info regarding metastore summary.
DatabaseProduct	getDbProduct()
String	getSelectQueryForMetastoreSummary()
String	lockTable(String txnLockTable, boolean shared) Returns the SQL query to lock the given table name in either shared/exclusive mode
PreparedStatement	prepareStmtWithParameters(Connection dbConn, String sql, List<String> parameters) Make PreparedStatement object with list of String type parameters to be set.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SQLGenerator

public SQLGenerator(DatabaseProduct dbProduct,
                    org.apache.hadoop.conf.Configuration conf)

Method Detail

createInsertValuesPreparedStmt

public List<PreparedStatement> createInsertValuesPreparedStmt(Connection dbConn,
                                                              String tblColumns,
                                                              List<String> rows,
                                                              List<List<String>> paramsList)
                                                       throws SQLException

Generates "Insert into T(a,b,c) values(1,2,'f'),(3,4,'c')" for appropriate DB

Parameters:

tblColumns - e.g. "T(a,b,c)"

rows - e.g. list of Strings like 3,4,'d'

paramsList - List of parameters which in turn is list of Strings to be set in PreparedStatement object

Returns:

List PreparedStatement objects for fully formed INSERT INTO ... statements

Throws:

SQLException

createInsertValuesStmt

public List<String> createInsertValuesStmt(String tblColumns,
                                           List<String> rows)

Generates "Insert into T(a,b,c) values(1,2,'f'),(3,4,'c')" for appropriate DB.

Parameters:

tblColumns - e.g. "T(a,b,c)"

rows - e.g. list of Strings like 3,4,'d'

Returns:

fully formed INSERT INTO ... statements

addForUpdateClause

public String addForUpdateClause(String selectStatement)
                          throws MetaException

Given a selectStatement, decorated it with FOR UPDATE or semantically equivalent construct. If the DB doesn't support, return original select.

Throws:

MetaException

addLimitClause

public String addLimitClause(int numRows,
                             String noSelectsqlQuery)
                      throws MetaException

Suppose you have a query "select a,b from T" and you want to limit the result set to the first 5 rows. The mechanism to do that differs in different DBs. Make noSelectsqlQuery to be "a,b from T" and this method will return the appropriately modified row limiting query.

Note that if noSelectsqlQuery contains a join, you must make sure that all columns are unique for Oracle.

Throws:

MetaException

lockTable

public String lockTable(String txnLockTable,
                        boolean shared)
                 throws MetaException

Returns the SQL query to lock the given table name in either shared/exclusive mode

Parameters:

txnLockTable -

shared -

Returns:

Throws:

MetaException

prepareStmtWithParameters

public PreparedStatement prepareStmtWithParameters(Connection dbConn,
                                                   String sql,
                                                   List<String> parameters)
                                            throws SQLException

Make PreparedStatement object with list of String type parameters to be set. It is assumed the input sql string have the number of "?" equal to number of parameters passed as input.

Parameters:

dbConn - - Connection object

sql - - SQL statement with "?" for input parameters.

parameters - - List of String type parameters to be set in PreparedStatement object

Returns:

PreparedStatement type object

Throws:

SQLException

getCreateQueriesForMetastoreSummary

public List<String> getCreateQueriesForMetastoreSummary()

Create or replace a view that stores all the info regarding metastore summary.

Returns:

getSelectQueryForMetastoreSummary

public String getSelectQueryForMetastoreSummary()

getDbProduct

public DatabaseProduct getDbProduct()

addEscapeCharacters

public String addEscapeCharacters(String s)

createTxnLockStatement

public String createTxnLockStatement(boolean shared)
                              throws MetaException

Creates a lock statement for open/commit transaction based on the dbProduct in shared read / exclusive mode.

Parameters:

shared - shared or exclusive lock

Returns:

sql statement to execute

Throws:

MetaException - if the dbProduct is unknown