java.lang.Object
- org.tentackle.sql.backends.AbstractBackend
- - org.tentackle.sql.backends.AbstractSql92Backend
  - - org.tentackle.sql.backends.Postgres

All Implemented Interfaces:: Backend

@Service(Backend.class)
public class Postgres
extends AbstractSql92Backend

Backend for Postgres.

Author:: harald

Field Summary

Fields
Modifier and Type	Field	Description
`static String`	`DEFAULT_SCHEMA`	postgres' default schema.
`static String[]`	`RESERVED_WORDS_PG`	array of additional reserved words.
`static String`	`SQL_LIMIT`	LIMIT string.
`static String`	`SQL_LIMIT_PAR`	LIMIT ? string.
`static String`	`SQL_OFFSET`	OFFSET string.
`static String`	`SQL_OFFSET_PAR`	OFFSET ? string.

Fields inherited from class org.tentackle.sql.backends.AbstractSql92Backend
RESERVED_WORDS_SQL92, SQL_COALESCE, SQL_FOR_UPDATE

Fields inherited from class org.tentackle.sql.backends.AbstractBackend
TYPE_BIGINT, TYPE_BIT, TYPE_BLOB, TYPE_BOOL, TYPE_BOOLEAN, TYPE_BYTE, TYPE_BYTEA, TYPE_CHAR_1, TYPE_CLOB, TYPE_DATE, TYPE_DATETIME, TYPE_DATETIME_YEAR_TO_SECOND, TYPE_DECIMAL, TYPE_DECIMAL_19, TYPE_DOUBLE, TYPE_FLOAT, TYPE_FLOAT4, TYPE_FLOAT8, TYPE_INT, TYPE_INT2, TYPE_INT4, TYPE_INT8, TYPE_INTEGER, TYPE_NCHAR_1, TYPE_NUMBER, TYPE_NUMBER_1, TYPE_NUMBER_10, TYPE_NUMBER_19, TYPE_NUMBER_5, TYPE_NVARCHAR, TYPE_NVARCHAR_MAX, TYPE_REAL, TYPE_SMALLFLOAT, TYPE_SMALLINT, TYPE_TEXT, TYPE_TIME, TYPE_TIMESTAMP, TYPE_TINYINT, TYPE_VARBINARY_MAX, TYPE_VARCHAR

Fields inherited from interface org.tentackle.sql.Backend
SQL_ALLSTAR, SQL_ALTER_COLUMN, SQL_ALTER_INDEX, SQL_ALTER_TABLE, SQL_AND, SQL_ANDNOT, SQL_ARRAY_ALL, SQL_ARRAY_ALL_PAR, SQL_ARRAY_ANY, SQL_ARRAY_ANY_PAR, SQL_ARRAY_IN, SQL_ARRAY_IN_PAR, SQL_ARRAY_NOT_IN, SQL_ARRAY_NOT_IN_PAR, SQL_ARRAY_PAR, SQL_COMMA, SQL_COMMA_PAR, SQL_DELETE, SQL_EQUAL, SQL_EQUAL_PAR, SQL_EQUAL_PAR_COMMA, SQL_EQUAL_ZERO, SQL_EXISTS, SQL_FROM, SQL_GREATER, SQL_GREATER_PAR, SQL_GREATEROREQUAL, SQL_GREATEROREQUAL_PAR, SQL_GROUPBY, SQL_IF_EXISTS, SQL_INSERT_INTO, SQL_INSERT_VALUES, SQL_ISNOTNULL, SQL_ISNULL, SQL_LEFT_PARENTHESIS, SQL_LESS, SQL_LESS_PAR, SQL_LESSOREQUAL, SQL_LESSOREQUAL_PAR, SQL_LIKE, SQL_LIKE_PAR, SQL_MAX, SQL_MIN, SQL_NOT, SQL_NOTEQUAL, SQL_NOTEQUAL_PAR, SQL_NOTEQUAL_ZERO, SQL_NOTLIKE, SQL_NOTLIKE_PAR, SQL_OR, SQL_ORDERBY, SQL_ORNOT, SQL_PAR, SQL_PAR_COMMA, SQL_PLUS_ONE, SQL_RIGHT_PARENTHESIS, SQL_SELECT, SQL_SELECT_ALL_FROM, SQL_SET, SQL_SORTASC, SQL_SORTDESC, SQL_UPDATE, SQL_WHERE, SQL_WHEREALL, SQL_WHEREAND, SQL_WHERENOTHING, SQL_WHEREOR

Constructor Summary

Constructors
Constructor Description

Postgres()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`buildSelectSql(StringBuilder sqlBuilder, boolean writeLock, int limit, int offset)`	Creates a select statement string from an inner sql string.
`ColumnMetaData`	`createColumnMetaData(TableMetaData tableMetaData)`	Creates a column meta data instance.
`IndexColumnMetaData`	`createIndexColumnMetaData(IndexMetaData indexMetaData)`	Creates an index column meta data instance.
`IndexMetaData`	`createIndexMetaData(TableMetaData tableMetaData)`	Creates an index meta data instance.
`protected String`	`extractWhereClause(String sql, int whereOffset)`	Extracts the where clause from a given sql.
`String`	`getBackendId(Connection connection)`	Determines the unique id or name used by the backend for a given connection.
`String`	`getDefaultSchema()`	Gets the default schema name. Some backends store the objects in a default schema, if no explicit schema is given.
`int`	`getDefaultSize(SqlType sqlType)`	Gets the default size if no size given in model.
`String`	`getDriverClassName()`	Gets the JDBC driver class name.
`int`	`getMaxSize(SqlType sqlType)`	Returns the maximum size for a given SQL-type.
`MigrationStrategy[]`	`getMigrationStrategy(ColumnMetaData column, String columnName, String comment, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue)`	Determines the best migration strategy.
`String`	`getName()`	Gets the name of the backend.
`Set<String>`	`getReservedWords()`	Gets the list of reserved words for this backend.
`boolean`	`isArrayOperatorSupported(String operator)`	Returns whether the backend supports given array operator.
`boolean`	`isClobSupported()`	Returns whether the backend support CLOB types. If not, it will be emulated as VARCHAR with the maximum possible size.
`protected boolean`	`isDropIfExistsSupported()`	Adds "IF EXISTS" to drop clauses, if supported by the backend. Makes migration a little more robust in case the same SQL scripts are applied to different databases than those used to generate the migration scripts for.
`boolean`	`isFilteredIndexSupported()`	Returns whether backend supports filtered indexes.
`boolean`	`isFunctionBasedIndexSupported()`	Returns whether function based indexes are supported.
`boolean`	`isMatchingUrl(String url)`	Checks whether the backend belongs to the given jdbc url. If multiple backend implementations are provided for the same database type, only one backend should match the URL.
`boolean`	`isReleaseSavepointSupported()`	Returns whether the backend supports releasing savepoints explicitly.
`boolean`	`isReservedSchemaName(String name)`	Checks whether this is a reserved schema name for this backend.
`boolean`	`isTransientTransactionException(SQLException ex)`	Determines whether exception is transient and retrying the transaction may succeed. Typical transient exceptions are thrown when a deadlock is detected or when serialized transaction isolation is used.
`SqlType[]`	`jdbcTypeToSqlType(int jdbcType, int size, int scale)`	Converts the JDBC data type integer to a tentackle backend SqlTypes.
`boolean`	`needAliasForSubselect()`	Returns whether backend needs an alias for a subselect.
`boolean`	`needTxForFetchsize()`	Checks for the (postgres) bug that fetchsize is ignored if not within a new transaction.
`int`	`setLeadingSelectParameters(BackendPreparedStatement stmt, int limit, int offset)`	Sets optional parameters before applying the original parameters.
`int`	`setTrailingSelectParameters(BackendPreparedStatement stmt, int index, int limit, int offset)`	Sets optional parameters after applying the original parameters.
`String`	`sqlAlterColumnNullConstraint(String tableName, String columnName, boolean nullable)`	Generates sql code to change the null-constraint of a column.
`String`	`sqlAlterColumnType(String tableName, String columnName, String comment, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue)`	Generates sql code to change the datatype of a column.
`String`	`sqlCreateColumnComment(String tableName, String columnName, String comment)`	Generates SQL code to create the comment for an attribute.
`String`	`sqlCreateTableComment(String tableName, String comment)`	Generates SQL code to create the comment for a table.
`String`	`sqlNextFromSequene(String name)`	Creates the SQL string to retrieve the next id from a sequence.
`String`	`sqlTypeToString(SqlType sqlType, int size)`	Converts the java SQL-type to the database type name.
`boolean`	`supportsSequences()`	True if backend provides transactionless sequences.
`String`	`toInternalType(String sqlTypeName)`	Converts a backend specific type name to an internal name used by driver specific methods.

Methods inherited from class org.tentackle.sql.backends.AbstractSql92Backend
getCoalesceKeyword, sqlCreateForeignKey, sqlDropForeignKey

Methods inherited from class org.tentackle.sql.backends.AbstractBackend
allowsExpressionsReferringToTablesBeingUpdated, assertValidName, buildSelectSql, columnTypeNullDefaultToString, columnTypeToString, createConnection, createPassword, createTableMetaData, getEmptyString, getMaxScale, getMetaData, getModelMetaData, getTableHeaders, getTableMetaData, isCommunicationLinkException, isConstraintException, isDefaultEqual, isDropIfExistsEnabled, isExceptionErrorCodeMatching, isExceptionStateMatching, isExceptionStateStartingWith, isMatchingName, isReservedTableName, isTemporaryName, needSetLongWorkaround, normalizeDefault, optimizeSql, setArray, setDropIfExistsEnabled, sqlAddColumn, sqlAlterColumnComment, sqlAlterColumnDefault, sqlAlterTableComment, sqlAsBeforeTableAlias, sqlComment, sqlCreateColumn, sqlCreateIndex, sqlCreateTableAttributeWithoutComment, sqlCreateTableClosing, sqlCreateTableIntro, sqlCreateTableIntroWithoutComment, sqlDropColumn, sqlDropIndex, sqlDropTable, sqlFunction, sqlJoin, sqlJoinSelects, sqlJoinSelects, sqlRenameAndAlterColumnType, sqlRenameColumn, sqlRenameIndex, sqlRenameTable, sqlRequiresExtraCommit, sqlResultSetIsClosedSupported, sqlUpdateToNotNull, toQuotedString, toString, valueToLiteral

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - DEFAULT_SCHEMA
```
public static final String DEFAULT_SCHEMA
```
    postgres' default schema.
    
    See Also:
    
    Constant Field Values
  - SQL_LIMIT
```
public static final String SQL_LIMIT
```
    LIMIT string.
    
    See Also:
    
    Constant Field Values
  - SQL_OFFSET
```
public static final String SQL_OFFSET
```
    OFFSET string.
    
    See Also:
    
    Constant Field Values
  - SQL_LIMIT_PAR
```
public static final String SQL_LIMIT_PAR
```
    LIMIT ? string.
    
    See Also:
    
    Constant Field Values
  - SQL_OFFSET_PAR
```
public static final String SQL_OFFSET_PAR
```
    OFFSET ? string.
    
    See Also:
    
    Constant Field Values
  - RESERVED_WORDS_PG
```
public static final String[] RESERVED_WORDS_PG
```
    array of additional reserved words.
- Constructor Detail
  - Postgres
```
public Postgres()
```
- Method Detail
  - getReservedWords
```
public Set<String> getReservedWords()
```
    Description copied from interface: Backend
    
    Gets the list of reserved words for this backend.
    
    Specified by:
    
    getReservedWords in interface Backend
    
    Overrides:
    
    getReservedWords in class AbstractSql92Backend
    
    Returns:
    
    the list of reserved words
  - isMatchingUrl
```
public boolean isMatchingUrl(String url)
```
    Description copied from interface: Backend
    
    Checks whether the backend belongs to the given jdbc url.
    If multiple backend implementations are provided for the same database type, only one backend should match the URL. The others must be selected via name.
    
    Parameters:
    
    url - the jdbc url
    
    Returns:
    
    true if matches
  - getName
```
public String getName()
```
    Description copied from interface: Backend
    
    Gets the name of the backend.
    
    Returns:
    
    the name
  - getDriverClassName
```
public String getDriverClassName()
```
    Description copied from interface: Backend
    
    Gets the JDBC driver class name.
    
    Returns:
    
    the class name
  - getBackendId
```
public String getBackendId(Connection connection)
```
    Description copied from interface: Backend
    
    Determines the unique id or name used by the backend for a given connection.
    Useful to figure out the corresponding ManagedConnection from the backend's logfiles.
    
    Parameters:
    
    connection - the jdbc connection
    
    Returns:
    
    the backend id, null if none
  - isReleaseSavepointSupported
```
public boolean isReleaseSavepointSupported()
```
    Description copied from interface: Backend
    
    Returns whether the backend supports releasing savepoints explicitly. If not, the savepoints are released when the transaction finishs.
    
    Specified by:
    
    isReleaseSavepointSupported in interface Backend
    
    Overrides:
    
    isReleaseSavepointSupported in class AbstractBackend
    
    Returns:
    
    true if release is supported, else false
  - isReservedSchemaName
```
public boolean isReservedSchemaName(String name)
```
    Description copied from interface: Backend
    
    Checks whether this is a reserved schema name for this backend.
    
    Specified by:
    
    isReservedSchemaName in interface Backend
    
    Overrides:
    
    isReservedSchemaName in class AbstractBackend
    
    Parameters:
    
    name - the schema name
    
    Returns:
    
    true if reserved by backend
  - isTransientTransactionException
```
public boolean isTransientTransactionException(SQLException ex)
```
    Description copied from interface: Backend
    
    Determines whether exception is transient and retrying the transaction may succeed.
    Typical transient exceptions are thrown when a deadlock is detected or when serialized transaction isolation is used.
    Other transient errors are not covered by this method (e.g. connection timeouts, etc...).
    
    Specified by:
    
    isTransientTransactionException in interface Backend
    
    Overrides:
    
    isTransientTransactionException in class AbstractBackend
    
    Parameters:
    
    ex - the exception
    
    Returns:
    
    true if retrying the transaction may succeed
  - isClobSupported
```
public boolean isClobSupported()
```
    Description copied from interface: Backend
    
    Returns whether the backend support CLOB types.
    If not, it will be emulated as VARCHAR with the maximum possible size.
    
    Specified by:
    
    isClobSupported in interface Backend
    
    Overrides:
    
    isClobSupported in class AbstractBackend
    
    Returns:
    
    true if supported, false if treat as varchar
  - isFilteredIndexSupported
```
public boolean isFilteredIndexSupported()
```
    Description copied from interface: Backend
    
    Returns whether backend supports filtered indexes.
    
    Specified by:
    
    isFilteredIndexSupported in interface Backend
    
    Overrides:
    
    isFilteredIndexSupported in class AbstractBackend
    
    Returns:
    
    true if supported, false if model will raise an error if filtered index is used
  - isFunctionBasedIndexSupported
```
public boolean isFunctionBasedIndexSupported()
```
    Description copied from interface: Backend
    
    Returns whether function based indexes are supported.
    
    Specified by:
    
    isFunctionBasedIndexSupported in interface Backend
    
    Overrides:
    
    isFunctionBasedIndexSupported in class AbstractBackend
    
    Returns:
    
    true if supported
  - needTxForFetchsize
```
public boolean needTxForFetchsize()
```
    Description copied from interface: Backend
    
    Checks for the (postgres) bug that fetchsize is ignored if not within a new transaction.
    
    Specified by:
    
    needTxForFetchsize in interface Backend
    
    Overrides:
    
    needTxForFetchsize in class AbstractBackend
    
    Returns:
    
    true if start tx
  - needAliasForSubselect
```
public boolean needAliasForSubselect()
```
    Description copied from interface: Backend
    
    Returns whether backend needs an alias for a subselect.
    
    Specified by:
    
    needAliasForSubselect in interface Backend
    
    Overrides:
    
    needAliasForSubselect in class AbstractBackend
    
    Returns:
    
    true if subselect needs an alias.
  - buildSelectSql
```
public void buildSelectSql(StringBuilder sqlBuilder,
                           boolean writeLock,
                           int limit,
                           int offset)
```
    Description copied from interface: Backend
    
    Creates a select statement string from an inner sql string.
    sqlBuilder is anything as FROM... WHERE... ORDER BY....
    It is decorated with a leading SELECT plus optional clauses like for the given parameters.
    
    Specified by:
    
    buildSelectSql in interface Backend
    
    Overrides:
    
    buildSelectSql in class AbstractSql92Backend
    
    Parameters:
    
    sqlBuilder - the sql builder, initially containing the inner sql without leading SELECT.
    
    writeLock - true select should write lock
    
    limit - the limit value, ≤ 0 if no limit clause
    
    offset - the offset value, ≤ 0 if no offset clause
  - setLeadingSelectParameters
```
public int setLeadingSelectParameters(BackendPreparedStatement stmt,
                                      int limit,
                                      int offset)
```
    Description copied from interface: Backend
    
    Sets optional parameters before applying the original parameters.
    
    Specified by:
    
    setLeadingSelectParameters in interface Backend
    
    Overrides:
    
    setLeadingSelectParameters in class AbstractSql92Backend
    
    Parameters:
    
    stmt - the prepared statement
    
    limit - the limit value, ≤ 0 if no limit clause
    
    offset - the offset value, ≤ 0 if no offset clause
    
    Returns:
    
    the next parameter index
  - setTrailingSelectParameters
```
public int setTrailingSelectParameters(BackendPreparedStatement stmt,
                                       int index,
                                       int limit,
                                       int offset)
```
    Description copied from interface: Backend
    
    Sets optional parameters after applying the original parameters.
    
    Specified by:
    
    setTrailingSelectParameters in interface Backend
    
    Overrides:
    
    setTrailingSelectParameters in class AbstractSql92Backend
    
    Parameters:
    
    stmt - the prepared statement
    
    index - the first parameter index
    
    limit - the limit value, ≤ 0 if no limit clause
    
    offset - the offset value, ≤ 0 if no offset clause
    
    Returns:
    
    the next parameter index
  - createColumnMetaData
```
public ColumnMetaData createColumnMetaData(TableMetaData tableMetaData)
```
    Description copied from interface: Backend
    
    Creates a column meta data instance.
    
    Specified by:
    
    createColumnMetaData in interface Backend
    
    Overrides:
    
    createColumnMetaData in class AbstractBackend
    
    Parameters:
    
    tableMetaData - the table meta data this column belongs to
    
    Returns:
    
    the meta data
  - createIndexMetaData
```
public IndexMetaData createIndexMetaData(TableMetaData tableMetaData)
```
    Description copied from interface: Backend
    
    Creates an index meta data instance.
    
    Specified by:
    
    createIndexMetaData in interface Backend
    
    Overrides:
    
    createIndexMetaData in class AbstractBackend
    
    Parameters:
    
    tableMetaData - the table meta data this index belongs to
    
    Returns:
    
    the meta data
  - createIndexColumnMetaData
```
public IndexColumnMetaData createIndexColumnMetaData(IndexMetaData indexMetaData)
```
    Description copied from interface: Backend
    
    Creates an index column meta data instance.
    
    Specified by:
    
    createIndexColumnMetaData in interface Backend
    
    Overrides:
    
    createIndexColumnMetaData in class AbstractBackend
    
    Parameters:
    
    indexMetaData - the meta meta data this column belongs to
    
    Returns:
    
    the meta data
  - getMaxSize
```
public int getMaxSize(SqlType sqlType)
```
    Description copied from interface: Backend
    
    Returns the maximum size for a given SQL-type.
    
    Specified by:
    
    getMaxSize in interface Backend
    
    Overrides:
    
    getMaxSize in class AbstractBackend
    
    Parameters:
    
    sqlType - the SQL-type
    
    Returns:
    
    the maximum size, 0 if unlimited, -1 if type without size
  - getDefaultSize
```
public int getDefaultSize(SqlType sqlType)
```
    Description copied from interface: Backend
    
    Gets the default size if no size given in model.
    
    Specified by:
    
    getDefaultSize in interface Backend
    
    Overrides:
    
    getDefaultSize in class AbstractBackend
    
    Parameters:
    
    sqlType - the SQL-type
    
    Returns:
    
    the default size, 0 if no default size
  - getDefaultSchema
```
public String getDefaultSchema()
```
    Description copied from interface: Backend
    
    Gets the default schema name.
    Some backends store the objects in a default schema, if no explicit schema is given.
    
    Specified by:
    
    getDefaultSchema in interface Backend
    
    Overrides:
    
    getDefaultSchema in class AbstractBackend
    
    Returns:
    
    the defailt schema, null if none
  - jdbcTypeToSqlType
```
public SqlType[] jdbcTypeToSqlType(int jdbcType,
                                   int size,
                                   int scale)
```
    Description copied from interface: Backend
    
    Converts the JDBC data type integer to a tentackle backend SqlTypes.
    There may be more than one sqltype returned!
    
    Specified by:
    
    jdbcTypeToSqlType in interface Backend
    
    Overrides:
    
    jdbcTypeToSqlType in class AbstractBackend
    
    Parameters:
    
    jdbcType - the jdbc data type
    
    size - the column size
    
    scale - the column's scale
    
    Returns:
    
    the SqlTypes, empty array if no mapping available or no exact match (not generated by TT)
    
    See Also:
    
    Types
  - sqlTypeToString
```
public String sqlTypeToString(SqlType sqlType,
                              int size)
```
    Description copied from interface: Backend
    
    Converts the java SQL-type to the database type name.
    
    Specified by:
    
    sqlTypeToString in interface Backend
    
    Overrides:
    
    sqlTypeToString in class AbstractBackend
    
    Parameters:
    
    sqlType - the java sql type
    
    size - the column's size
    
    Returns:
    
    the corresponding type string
  - supportsSequences
```
public boolean supportsSequences()
```
    Description copied from interface: Backend
    
    True if backend provides transactionless sequences.
    
    Specified by:
    
    supportsSequences in interface Backend
    
    Overrides:
    
    supportsSequences in class AbstractSql92Backend
    
    Returns:
    
    true if database supports sequences
  - sqlNextFromSequene
```
public String sqlNextFromSequene(String name)
```
    Description copied from interface: Backend
    
    Creates the SQL string to retrieve the next id from a sequence.
    
    Specified by:
    
    sqlNextFromSequene in interface Backend
    
    Overrides:
    
    sqlNextFromSequene in class AbstractSql92Backend
    
    Parameters:
    
    name - the name of the sequence
    
    Returns:
    
    the SQL code
  - sqlCreateTableComment
```
public String sqlCreateTableComment(String tableName,
                                    String comment)
```
    Description copied from interface: Backend
    
    Generates SQL code to create the comment for a table.
    
    Specified by:
    
    sqlCreateTableComment in interface Backend
    
    Overrides:
    
    sqlCreateTableComment in class AbstractBackend
    
    Parameters:
    
    tableName - the table name
    
    comment - optional comment, null if none
    
    Returns:
    
    the SQL code, empty string if comment is created via Backend.sqlCreateTableIntro(java.lang.String, java.lang.String) or Backend.sqlCreateTableClosing(java.lang.String, java.lang.String)
  - sqlCreateColumnComment
```
public String sqlCreateColumnComment(String tableName,
                                     String columnName,
                                     String comment)
```
    Description copied from interface: Backend
    
    Generates SQL code to create the comment for an attribute.
    
    Specified by:
    
    sqlCreateColumnComment in interface Backend
    
    Overrides:
    
    sqlCreateColumnComment in class AbstractBackend
    
    Parameters:
    
    tableName - the table name
    
    columnName - the column name
    
    comment - optional comment, null if none
    
    Returns:
    
    the SQL code, empty string if comment is created via Backend.sqlCreateColumn(java.lang.String, java.lang.String, org.tentackle.sql.SqlType, int, int, boolean, java.lang.Object, boolean, boolean)
  - sqlAlterColumnType
```
public String sqlAlterColumnType(String tableName,
                                 String columnName,
                                 String comment,
                                 SqlType sqlType,
                                 int size,
                                 int scale,
                                 boolean nullable,
                                 Object defaultValue)
```
    Description copied from interface: Backend
    
    Generates sql code to change the datatype of a column.
    
    Specified by:
    
    sqlAlterColumnType in interface Backend
    
    Overrides:
    
    sqlAlterColumnType in class AbstractBackend
    
    Parameters:
    
    tableName - the tablename
    
    columnName - the new column name
    
    comment - optional comment, null if none
    
    sqlType - the JDBC sql type
    
    size - the optional size
    
    scale - the optional scale
    
    nullable - true if NULL, else NOT NULL
    
    defaultValue - the optional default value
    
    Returns:
    
    the SQL code
  - sqlAlterColumnNullConstraint
```
public String sqlAlterColumnNullConstraint(String tableName,
                                           String columnName,
                                           boolean nullable)
```
    Description copied from interface: Backend
    
    Generates sql code to change the null-constraint of a column.
    
    Specified by:
    
    sqlAlterColumnNullConstraint in interface Backend
    
    Overrides:
    
    sqlAlterColumnNullConstraint in class AbstractBackend
    
    Parameters:
    
    tableName - the tablename
    
    columnName - the new column name
    
    nullable - true if NULL, else NOT NULL
    
    Returns:
    
    the SQL code, null if need Backend.sqlAlterColumnType(java.lang.String, java.lang.String, java.lang.String, org.tentackle.sql.SqlType, int, int, boolean, java.lang.Object)
  - toInternalType
```
public String toInternalType(String sqlTypeName)
```
    Description copied from interface: Backend
    
    Converts a backend specific type name to an internal name used by driver specific methods.
    
    Specified by:
    
    toInternalType in interface Backend
    
    Overrides:
    
    toInternalType in class AbstractBackend
    
    Parameters:
    
    sqlTypeName - the original type used in SQL scripts
    
    Returns:
    
    the JDBC internal name
  - isArrayOperatorSupported
```
public boolean isArrayOperatorSupported(String operator)
```
    Description copied from interface: Backend
    
    Returns whether the backend supports given array operator.
    
    Specified by:
    
    isArrayOperatorSupported in interface Backend
    
    Overrides:
    
    isArrayOperatorSupported in class AbstractBackend
    
    Parameters:
    
    operator - the array operator
    
    Returns:
    
    true if supported
  - getMigrationStrategy
```
public MigrationStrategy[] getMigrationStrategy(ColumnMetaData column,
                                                String columnName,
                                                String comment,
                                                SqlType sqlType,
                                                int size,
                                                int scale,
                                                boolean nullable,
                                                Object defaultValue)
```
    Description copied from interface: Backend
    
    Determines the best migration strategy.
    
    Specified by:
    
    getMigrationStrategy in interface Backend
    
    Overrides:
    
    getMigrationStrategy in class AbstractBackend
    
    Parameters:
    
    column - old column meta data
    
    columnName - new column name
    
    comment - new comment
    
    sqlType - new sql type
    
    size - new size
    
    scale - new scale
    
    nullable - new nullable
    
    defaultValue - new default
    
    Returns:
    
    the strategies in order to achieve the migration
  - extractWhereClause
```
protected String extractWhereClause(String sql,
                                    int whereOffset)
```
    Description copied from class: AbstractBackend
    
    Extracts the where clause from a given sql.
    
    Overrides:
    
    extractWhereClause in class AbstractBackend
    
    Parameters:
    
    sql - the sql statement
    
    whereOffset - the location of WHERE in sql
    
    Returns:
    
    the where clause without the keyword WHERE
  - isDropIfExistsSupported
```
protected boolean isDropIfExistsSupported()
```
    Description copied from class: AbstractBackend
    
    Adds "IF EXISTS" to drop clauses, if supported by the backend.
    Makes migration a little more robust in case the same SQL scripts are applied to different databases than those used to generate the migration scripts for.
    
    Overrides:
    
    isDropIfExistsSupported in class AbstractBackend
    
    Returns:
    
    true if supported

Class Postgres

Field Summary

Fields inherited from class org.tentackle.sql.backends.AbstractSql92Backend

Fields inherited from class org.tentackle.sql.backends.AbstractBackend

Fields inherited from interface org.tentackle.sql.Backend

Constructor Summary

Method Summary

Methods inherited from class org.tentackle.sql.backends.AbstractSql92Backend

Methods inherited from class org.tentackle.sql.backends.AbstractBackend

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_SCHEMA

SQL_LIMIT

SQL_OFFSET

SQL_LIMIT_PAR

SQL_OFFSET_PAR

RESERVED_WORDS_PG

Constructor Detail

Postgres

Method Detail

getReservedWords

isMatchingUrl

getName

getDriverClassName

getBackendId

isReleaseSavepointSupported

isReservedSchemaName

isTransientTransactionException

isClobSupported

isFilteredIndexSupported

isFunctionBasedIndexSupported

needTxForFetchsize

needAliasForSubselect

buildSelectSql

setLeadingSelectParameters

setTrailingSelectParameters

createColumnMetaData

createIndexMetaData

createIndexColumnMetaData

getMaxSize

getDefaultSize

getDefaultSchema

jdbcTypeToSqlType

sqlTypeToString

supportsSequences

sqlNextFromSequene

sqlCreateTableComment

sqlCreateColumnComment

sqlAlterColumnType

sqlAlterColumnNullConstraint

toInternalType

isArrayOperatorSupported

getMigrationStrategy

extractWhereClause

isDropIfExistsSupported