public class DB2Dialect extends Dialect
An SQL dialect for DB2.
CLOSED_QUOTE, DEFAULT_BATCH_SIZE, LEGACY_LOB_MERGE_STRATEGY, NEW_LOCATOR_LOB_MERGE_STRATEGY, NO_BATCH, QUOTE, STANDARD_DEFAULT_BATCH_LOAD_SIZING_STRATEGY, STREAM_XFER_LOB_MERGE_STRATEGY
Constructor and Description |
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DB2Dialect()
Constructs a DB2Dialect
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Modifier and Type | Method and Description |
---|---|
SQLExceptionConversionDelegate |
buildSQLExceptionConversionDelegate()
Build an instance of a
SQLExceptionConversionDelegate for
interpreting dialect-specific error or SQLState codes. |
int |
convertToFirstRowValue(int zeroBasedFirstResult)
Hibernate APIs explicitly state that setFirstResult() should be a zero-based offset.
|
boolean |
doesReadCommittedCauseWritersToBlockReaders()
For the underlying database, is READ_COMMITTED isolation implemented by
forcing readers to wait for write locks to be released?
|
boolean |
dropConstraints()
Do we need to drop constraints before dropping tables in this dialect?
|
String |
getAddColumnString()
The syntax used to add a column to a table (optional).
|
String |
getCreateSequenceString(String sequenceName)
Typically dialects which support sequences can create a sequence
with a single command.
|
String |
getCrossJoinSeparator()
Returns the separator to use for defining cross joins when translating HQL queries.
|
String |
getCurrentTimestampSelectString()
Retrieve the command used to retrieve the current timestamp from the
database.
|
MultiTableBulkIdStrategy |
getDefaultMultiTableBulkIdStrategy() |
String |
getDropSequenceString(String sequenceName)
Typically dialects which support sequences can drop a sequence
with a single command.
|
String |
getForUpdateString()
Get the string to append to SELECT statements to acquire locks
for this dialect.
|
IdentityColumnSupport |
getIdentityColumnSupport()
Get the appropriate
IdentityColumnSupport |
LimitHandler |
getLimitHandler()
Returns the delegate managing LIMIT clause.
|
String |
getLimitString(String sql,
int offset,
int limit)
Given a limit and an offset, apply the limit clause to the query.
|
String |
getLowercaseFunction()
The name of the SQL function that transforms a string to
lowercase
|
String |
getNotExpression(String expression)
Negate an expression
|
String |
getQuerySequencesString()
Get the select command used retrieve the names of all sequences.
|
ResultSet |
getResultSet(CallableStatement ps)
Given a callable statement previously processed by
Dialect.registerResultSetOutParameter(java.sql.CallableStatement, int) ,
extract the ResultSet from the OUT parameter. |
String |
getSelectClauseNullString(int sqlType)
Given a
Types type code, determine an appropriate
null value to use in a select clause. |
String |
getSelectSequenceNextValString(String sequenceName)
Generate the select expression fragment that will retrieve the next
value of a sequence as part of another (typically DML) statement.
|
String |
getSequenceNextValString(String sequenceName)
Generate the appropriate select statement to to retrieve the next value
of a sequence.
|
protected SqlTypeDescriptor |
getSqlTypeDescriptorOverride(int sqlCode)
Returns the
SqlTypeDescriptor that should be used to handle the given JDBC type code. |
UniqueDelegate |
getUniqueDelegate()
Get the UniqueDelegate supported by this dialect
|
boolean |
isCurrentTimestampSelectStringCallable()
Should the value returned by
Dialect.getCurrentTimestampSelectString()
be treated as callable. |
int |
registerResultSetOutParameter(CallableStatement statement,
int col)
Registers a parameter (either OUT, or the new REF_CURSOR param type available in Java 8) capable of
returning
ResultSet by position. |
String |
renderOrderByElement(String expression,
String collation,
String order,
NullPrecedence nullPrecedence)
Handle DB2 "support" for null precedence…
|
boolean |
requiresCastingOfParametersInSelectClause()
Does this dialect require that parameters appearing in the <tt>SELECT</tt> clause be wrapped in <tt>cast()</tt>
calls to tell the db parser the expected type.
|
boolean |
supportsCommentOn()
Does this dialect/database support commenting on tables, columns, etc?
|
boolean |
supportsCurrentTimestampSelection()
Does this dialect support a way to retrieve the database’s current
timestamp value?
|
boolean |
supportsEmptyInList()
Does this dialect support empty IN lists?
<p/>
For example, is [where XYZ in ()] a supported construct?
|
boolean |
supportsExistsInSelect()
Does the dialect support an exists statement in the select clause?
|
boolean |
supportsLimit()
Does this dialect support some form of limiting query results
via a SQL clause?
|
boolean |
supportsLobValueChangePropogation()
Does the dialect support propagating changes to LOB
values back to the database? Talking about mutating the
internal value of the locator as opposed to supplying a new
locator instance…
<p/>
For BLOBs, the internal value might be changed by:
Blob.setBinaryStream(long) ,
Blob.setBytes(long, byte[]) ,
Blob.setBytes(long, byte[], int, int) ,
or Blob.truncate(long) . |
boolean |
supportsLockTimeouts()
Informational metadata about whether this dialect is known to support
specifying timeouts for requested lock acquisitions.
|
boolean |
supportsOuterJoinForUpdate()
Does this dialect support <tt>FOR UPDATE</tt> in conjunction with
outer joined rows?
|
boolean |
supportsParametersInInsertSelect()
Does this dialect support parameters within the <tt>SELECT</tt> clause of
<tt>INSERT … SELECT …</tt> statements?
|
boolean |
supportsPartitionBy()
Does the underlying database support partition by
|
boolean |
supportsPooledSequences()
Does this dialect support "pooled" sequences.
|
boolean |
supportsResultSetPositionQueryMethodsOnForwardOnlyCursor()
Does this dialect support asking the result set its positioning
information on forward only cursors.
|
boolean |
supportsSequences()
Does this dialect support sequences?
|
boolean |
supportsTupleDistinctCounts()
Does this dialect support
count(distinct a,b) ? |
boolean |
supportsUnionAll()
Does this dialect support UNION ALL, which is generally a faster
variant of UNION?
|
boolean |
supportsVariableLimit()
Does this dialect support bind variables (i.e., prepared statement
parameters) for its limit/offset?
|
boolean |
useMaxForLimit()
Does the <tt>LIMIT</tt> clause take a "maximum" row number instead
of a total number of returned rows?
<p/>
This is easiest understood via an example.
|
addSqlHintOrComment, appendLockHint, appendLockHint, applyLocksToSql, areStringComparisonsCaseInsensitive, augmentRecognizedTableTypes, bindLimitParametersFirst, bindLimitParametersInReverseOrder, buildIdentifierHelper, buildSQLExceptionConverter, canCreateCatalog, canCreateSchema, cast, cast, cast, closeQuote, contributeTypes, createCaseFragment, createOuterJoinFragment, defaultScrollMode, doesRepeatableReadCauseReadersToBlockWriters, escapeLiteral, forceLimitUsage, forceLobAsLastValue, forUpdateOfColumns, getAddColumnSuffixString, getAddForeignKeyConstraintString, getAddForeignKeyConstraintString, getAddPrimaryKeyConstraintString, getAddUniqueConstraintString, getAlterTableString, getAuxiliaryDatabaseObjectExporter, getCallableStatementSupport, getCascadeConstraintsString, getCaseInsensitiveLike, getCastTypeName, getColumnAliasExtractor, getColumnComment, getCreateCatalogCommand, getCreateMultisetTableString, getCreateSchemaCommand, getCreateSequenceString, getCreateSequenceStrings, getCreateSequenceStrings, getCreateTableString, getCurrentSchemaCommand, getCurrentTimestampSQLFunctionName, getDefaultBatchLoadSizingStrategy, getDefaultProperties, getDialect, getDialect, getDropCatalogCommand, getDropForeignKeyString, getDropSchemaCommand, getDropSequenceStrings, getDropTableString, getForeignKeyExporter, getForUpdateNowaitString, getForUpdateNowaitString, getForUpdateSkipLockedString, getForUpdateSkipLockedString, getForUpdateString, getForUpdateString, getForUpdateString, getForUpdateString, getFunctions, getHibernateTypeName, getHibernateTypeName, getIndexExporter, getInExpressionCountLimit, getKeywords, getLimitString, getLobMergeStrategy, getLockingStrategy, getMaxAliasLength, getNameQualifierSupport, getNativeIdentifierGeneratorClass, getNativeIdentifierGeneratorStrategy, getNoColumnsInsertString, getNullColumnString, getQueryHintString, getQueryHintString, getReadLockString, getReadLockString, getResultSet, getResultSet, getSchemaNameResolver, getSelectGUIDString, getSequenceExporter, getSequenceInformationExtractor, getTableComment, getTableExporter, getTableTypeString, getTypeName, getTypeName, getUniqueKeyExporter, getViolatedConstraintNameExtracter, getWriteLockString, getWriteLockString, hasAlterTable, hasSelfReferentialForeignKeyBug, inlineLiteral, isJdbcLogWarningsEnabledByDefault, isLegacyLimitHandlerBehaviorEnabled, isLockTimeoutParameterized, isTypeNameRegistered, openQuote, prependComment, qualifyIndexName, quote, registerColumnType, registerColumnType, registerFunction, registerHibernateType, registerHibernateType, registerKeyword, registerResultSetOutParameter, remapSqlTypeDescriptor, replaceResultVariableInOrderByClauseWithPosition, requiresParensForTupleDistinctCounts, supportsBindAsCallableArgument, supportsCascadeDelete, supportsCaseInsensitiveLike, supportsCircularCascadeDeleteConstraints, supportsColumnCheck, supportsExpectedLobUsagePattern, supportsIfExistsAfterAlterTable, supportsIfExistsAfterConstraintName, supportsIfExistsAfterTableName, supportsIfExistsBeforeConstraintName, supportsIfExistsBeforeTableName, supportsLimitOffset, supportsNamedParameters, supportsNationalizedTypes, supportsNonQueryWithCTE, supportsNotNullUnique, supportsNoWait, supportsRowValueConstructorSyntax, supportsRowValueConstructorSyntaxInInList, supportsSkipLocked, supportsSubqueryOnMutatingTable, supportsSubselectAsInPredicateLHS, supportsTableCheck, supportsTupleCounts, supportsTuplesInSubqueries, supportsUnboundedLobLocatorMaterialization, supportsUnique, supportsUniqueConstraintInCreateAlterTable, supportsValuesList, toBooleanValueString, toString, transformSelectString, useFollowOnLocking, useFollowOnLocking, useInputStreamToInsertBlob
public String getLowercaseFunction()
Dialect
The name of the SQL function that transforms a string to lowercase
getLowercaseFunction
in class Dialect
public String getAddColumnString()
Dialect
The syntax used to add a column to a table (optional).
getAddColumnString
in class Dialect
public boolean dropConstraints()
Dialect
Do we need to drop constraints before dropping tables in this dialect?
dropConstraints
in class Dialect
public String getSequenceNextValString(String sequenceName)
Dialect
Generate the appropriate select statement to to retrieve the next value of a sequence. <p/> This should be a "stand alone" select statement.
getSequenceNextValString
in class Dialect
sequenceName
- the name of the sequencepublic String getSelectSequenceNextValString(String sequenceName) throws MappingException
Dialect
Generate the select expression fragment that will retrieve the next
value of a sequence as part of another (typically DML) statement.
<p/>
This differs from Dialect.getSequenceNextValString(String)
in that this
should return an expression usable within another statement.
getSelectSequenceNextValString
in class Dialect
sequenceName
- the name of the sequenceMappingException
- If sequences are not supported.public String getCreateSequenceString(String sequenceName)
Dialect
Typically dialects which support sequences can create a sequence
with a single command. This is convenience form of
Dialect.getCreateSequenceStrings(java.lang.String)
to help facilitate that.
<p/>
Dialects which support sequences and can create a sequence in a
single command need only override this method. Dialects
which support sequences but require multiple commands to create
a sequence should instead override Dialect.getCreateSequenceStrings(java.lang.String)
.
getCreateSequenceString
in class Dialect
sequenceName
- The name of the sequencepublic String getDropSequenceString(String sequenceName)
Dialect
Typically dialects which support sequences can drop a sequence
with a single command. This is convenience form of
Dialect.getDropSequenceStrings(java.lang.String)
to help facilitate that.
<p/>
Dialects which support sequences and can drop a sequence in a
single command need only override this method. Dialects
which support sequences but require multiple commands to drop
a sequence should instead override Dialect.getDropSequenceStrings(java.lang.String)
.
getDropSequenceString
in class Dialect
sequenceName
- The name of the sequencepublic boolean supportsSequences()
Dialect
Does this dialect support sequences?
supportsSequences
in class Dialect
public boolean supportsPooledSequences()
Dialect
Does this dialect support "pooled" sequences. Not aware of a better name for this. Essentially can we specify the initial and increment values?
supportsPooledSequences
in class Dialect
Dialect.getCreateSequenceStrings(String, int, int)
,
Dialect.getCreateSequenceString(String, int, int)
public String getQuerySequencesString()
Dialect
Get the select command used retrieve the names of all sequences.
getQuerySequencesString
in class Dialect
SchemaUpdate
public boolean supportsLimit()
Dialect
Does this dialect support some form of limiting query results via a SQL clause?
supportsLimit
in class Dialect
public boolean supportsVariableLimit()
Dialect
Does this dialect support bind variables (i.e., prepared statement parameters) for its limit/offset?
supportsVariableLimit
in class Dialect
public String getLimitString(String sql, int offset, int limit)
Dialect
Given a limit and an offset, apply the limit clause to the query.
getLimitString
in class Dialect
sql
- The query to which to apply the limit.offset
- The offset of the limitlimit
- The limit of the limit ;)public int convertToFirstRowValue(int zeroBasedFirstResult)
Hibernate APIs explicitly state that setFirstResult() should be a zero-based offset. Here we allow the
Dialect a chance to convert that value based on what the underlying db or driver will expect.
<p/>
NOTE: what gets passed into Dialect.getLimitString(String,int,int)
is the zero-based offset. Dialects which
do not Dialect.supportsVariableLimit()
should take care to perform any needed first-row-conversion calls prior
to injecting the limit values into the SQL string.
DB2 does have a one-based offset, however this was actually already handled in the limit string building (the '?+1' bit). To not mess up inheritors, I’ll leave that part alone and not touch the offset here.
convertToFirstRowValue
in class Dialect
zeroBasedFirstResult
- The user-supplied, zero-based first row offset.Query.setFirstResult(int)
,
Criteria.setFirstResult(int)
public String getForUpdateString()
Dialect
Get the string to append to SELECT statements to acquire locks for this dialect.
getForUpdateString
in class Dialect
public boolean useMaxForLimit()
Dialect
Does the <tt>LIMIT</tt> clause take a "maximum" row number instead of a total number of returned rows? <p/> This is easiest understood via an example. Consider you have a table with 20 rows, but you only want to retrieve rows number 11 through 20. Generally, a limit with offset would say that the offset = 11 and the limit = 10 (we only want 10 rows at a time); this is specifying the total number of returned rows. Some dialects require that we instead specify offset = 11 and limit = 20, where 20 is the "last" row we want relative to offset (i.e. total number of rows = 20 - 11 = 9) <p/> So essentially, is limit relative from offset? Or is limit absolute?
useMaxForLimit
in class Dialect
public boolean supportsOuterJoinForUpdate()
Dialect
Does this dialect support <tt>FOR UPDATE</tt> in conjunction with outer joined rows?
supportsOuterJoinForUpdate
in class Dialect
public boolean supportsExistsInSelect()
Dialect
Does the dialect support an exists statement in the select clause?
supportsExistsInSelect
in class Dialect
public boolean supportsLockTimeouts()
Dialect
Informational metadata about whether this dialect is known to support specifying timeouts for requested lock acquisitions.
supportsLockTimeouts
in class Dialect
public String getSelectClauseNullString(int sqlType)
Dialect
Given a Types
type code, determine an appropriate
null value to use in a select clause.
<p/>
One thing to consider here is that certain databases might
require proper casting for the nulls here since the select here
will be part of a UNION/UNION ALL.
getSelectClauseNullString
in class Dialect
sqlType
- The Types
type code.public boolean supportsUnionAll()
Dialect
Does this dialect support UNION ALL, which is generally a faster variant of UNION?
supportsUnionAll
in class Dialect
public int registerResultSetOutParameter(CallableStatement statement, int col) throws SQLException
Dialect
Registers a parameter (either OUT, or the new REF_CURSOR param type available in Java 8) capable of
returning ResultSet
by position. Pre-Java 8, registering such ResultSet-returning
parameters varied greatly across database and drivers; hence its inclusion as part of the Dialect contract.
registerResultSetOutParameter
in class Dialect
statement
- The callable statement.col
- The bind position at which to register the output param.SQLException
- Indicates problems registering the param.public ResultSet getResultSet(CallableStatement ps) throws SQLException
Dialect
Given a callable statement previously processed by Dialect.registerResultSetOutParameter(java.sql.CallableStatement, int)
,
extract the ResultSet
from the OUT parameter.
getResultSet
in class Dialect
ps
- The callable statement.SQLException
- Indicates problems extracting the result set.public boolean supportsCommentOn()
Dialect
Does this dialect/database support commenting on tables, columns, etc?
supportsCommentOn
in class Dialect
true
if commenting is supportedpublic MultiTableBulkIdStrategy getDefaultMultiTableBulkIdStrategy()
getDefaultMultiTableBulkIdStrategy
in class Dialect
public boolean supportsCurrentTimestampSelection()
Dialect
Does this dialect support a way to retrieve the database’s current timestamp value?
supportsCurrentTimestampSelection
in class Dialect
public String getCurrentTimestampSelectString()
Dialect
Retrieve the command used to retrieve the current timestamp from the database.
getCurrentTimestampSelectString
in class Dialect
public boolean isCurrentTimestampSelectStringCallable()
Dialect
Should the value returned by Dialect.getCurrentTimestampSelectString()
be treated as callable. Typically this indicates that JDBC escape
syntax is being used…
isCurrentTimestampSelectStringCallable
in class Dialect
Dialect.getCurrentTimestampSelectString()
return
is callable; false otherwise.public boolean supportsParametersInInsertSelect()
Does this dialect support parameters within the <tt>SELECT</tt> clause of <tt>INSERT … SELECT …</tt> statements?
<p/> NOTE : DB2 is know to support parameters in the <tt>SELECT</tt> clause, but only in casted form (seerequiresCastingOfParametersInSelectClause()
).supportsParametersInInsertSelect
in class Dialect
public boolean requiresCastingOfParametersInSelectClause()
Does this dialect require that parameters appearing in the <tt>SELECT</tt> clause be wrapped in <tt>cast()</tt> calls to tell the db parser the expected type.
<p/> DB2 in fact does require that parameters appearing in the select clause be wrapped in cast() calls to tell the DB parser the type of the select value.requiresCastingOfParametersInSelectClause
in class Dialect
public boolean supportsResultSetPositionQueryMethodsOnForwardOnlyCursor()
Dialect
Does this dialect support asking the result set its positioning
information on forward only cursors. Specifically, in the case of
scrolling fetches, Hibernate needs to use
ResultSet.isAfterLast()
and
ResultSet.isBeforeFirst()
. Certain drivers do not
allow access to these methods for forward only cursors.
<p/>
NOTE : this is highly driver dependent!
supportsResultSetPositionQueryMethodsOnForwardOnlyCursor
in class Dialect
ResultSet.isAfterLast()
and
ResultSet.isBeforeFirst()
are supported for forward
only cursors; false otherwise.public String getCrossJoinSeparator()
Dialect
Returns the separator to use for defining cross joins when translating HQL queries. <p/> Typically this will be either [<tt> cross join </tt>] or [<tt>, </tt>] <p/> Note that the spaces are important!
getCrossJoinSeparator
in class Dialect
public boolean supportsEmptyInList()
Dialect
Does this dialect support empty IN lists? <p/> For example, is [where XYZ in ()] a supported construct?
supportsEmptyInList
in class Dialect
public boolean supportsLobValueChangePropogation()
Dialect
Does the dialect support propagating changes to LOB
values back to the database? Talking about mutating the
internal value of the locator as opposed to supplying a new
locator instance…
<p/>
For BLOBs, the internal value might be changed by:
Blob.setBinaryStream(long)
,
Blob.setBytes(long, byte[])
,
Blob.setBytes(long, byte[], int, int)
,
or Blob.truncate(long)
.
<p/>
For CLOBs, the internal value might be changed by:
Clob.setAsciiStream(long)
,
Clob.setCharacterStream(long)
,
Clob.setString(long, String)
,
Clob.setString(long, String, int, int)
,
or Clob.truncate(long)
.
<p/>
NOTE : I do not know the correct answer currently for
databases which (1) are not part of the cruise control process
or (2) do not Dialect.supportsExpectedLobUsagePattern()
.
supportsLobValueChangePropogation
in class Dialect
public boolean doesReadCommittedCauseWritersToBlockReaders()
Dialect
For the underlying database, is READ_COMMITTED isolation implemented by forcing readers to wait for write locks to be released?
doesReadCommittedCauseWritersToBlockReaders
in class Dialect
public boolean supportsTupleDistinctCounts()
Dialect
Does this dialect support count(distinct a,b)
?
supportsTupleDistinctCounts
in class Dialect
protected SqlTypeDescriptor getSqlTypeDescriptorOverride(int sqlCode)
Dialect
Returns the SqlTypeDescriptor
that should be used to handle the given JDBC type code. Returns
null
if there is no override.
getSqlTypeDescriptorOverride
in class Dialect
sqlCode
- A Types
constant indicating the SQL column typeSqlTypeDescriptor
to use as an override, or null
if there is no override.public SQLExceptionConversionDelegate buildSQLExceptionConversionDelegate()
Dialect
Build an instance of a SQLExceptionConversionDelegate
for
interpreting dialect-specific error or SQLState codes.
<p/>
When Dialect.buildSQLExceptionConverter()
returns null, the default
SQLExceptionConverter
is used to interpret SQLState and
error codes. If this method is overridden to return a non-null value,
the default SQLExceptionConverter
will use the returned
SQLExceptionConversionDelegate
in addition to the following
standard delegates:
<ol>
<li>a "static" delegate based on the JDBC 4 defined SQLException hierarchy;</li>
<li>a delegate that interprets SQLState codes for either X/Open or SQL-2003 codes,
depending on java.sql.DatabaseMetaData#getSQLStateType</li>
</ol>
<p/>
It is strongly recommended that specific Dialect implementations override this
method, since interpretation of a SQL error is much more accurate when based on
the a vendor-specific ErrorCode rather than the SQLState.
<p/>
Specific Dialects may override to return whatever is most appropriate for that vendor.
buildSQLExceptionConversionDelegate
in class Dialect
public UniqueDelegate getUniqueDelegate()
Dialect
Get the UniqueDelegate supported by this dialect
getUniqueDelegate
in class Dialect
public String getNotExpression(String expression)
Dialect
Negate an expression
getNotExpression
in class Dialect
expression
- The expression to negatepublic LimitHandler getLimitHandler()
Dialect
Returns the delegate managing LIMIT clause.
getLimitHandler
in class Dialect
public String renderOrderByElement(String expression, String collation, String order, NullPrecedence nullPrecedence)
Handle DB2 "support" for null precedence…
renderOrderByElement
in class Dialect
expression
- The SQL order expression. In case of @OrderBy
annotation user receives property placeholder
(e.g. attribute name enclosed in '{' and '}' signs).collation
- Collation string in format collate IDENTIFIER
, or null
if expression has not been explicitly specified.order
- Order direction. Possible values: asc
, desc
, or null
if expression has not been explicitly specified.nullPrecedence
- Nulls precedence. Default value: NullPrecedence.NONE
.public IdentityColumnSupport getIdentityColumnSupport()
Dialect
Get the appropriate IdentityColumnSupport
getIdentityColumnSupport
in class Dialect
public boolean supportsPartitionBy()
Dialect
Does the underlying database support partition by
supportsPartitionBy
in class Dialect
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