Class JdbcDialectImpl
- java.lang.Object
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- mondrian.spi.impl.JdbcDialectImpl
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- All Implemented Interfaces:
Dialect
- Direct Known Subclasses:
AccessDialect
,Db2Dialect
,DerbyDialect
,FirebirdDialect
,GoogleBigQueryDialect
,HiveDialect
,HsqldbDialect
,InformixDialect
,IngresDialect
,InterbaseDialect
,LucidDbDialect
,MicrosoftSqlServerDialect
,MonetDbDialect
,MySqlDialect
,NeoviewDialect
,NuoDbDialect
,OracleDialect
,PdiDataServiceDialect
,PostgreSqlDialect
,SnowflakeDialect
,SybaseDialect
,TeradataDialect
,VerticaDialect
public class JdbcDialectImpl extends Object implements Dialect
Implementation ofDialect
based on a JDBC connection and metadata.If you are writing a class for a specific database dialect, we recommend that you use this as a base class, so your dialect class will be forwards-compatible. If methods are added to
Dialect
in future revisions, default implementations of those methods will be added to this class.Mondrian uses JdbcDialectImpl as a fallback if it cannot find a more specific dialect. JdbcDialectImpl reads properties from the JDBC driver's metadata, so can deduce some of the dialect's behavior.
- Since:
- Oct 10, 2008
- Author:
- jhyde
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Nested Class Summary
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Nested classes/interfaces inherited from interface mondrian.spi.Dialect
Dialect.DatabaseProduct, Dialect.Datatype
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Field Summary
Fields Modifier and Type Field Description protected Dialect.DatabaseProduct
databaseProduct
Major database product (or null if product is not a common one)protected boolean
permitsSelectNotInGroupBy
Indicates whether the database allows selection of columns not listed in the group by clause.protected String
productVersion
Product version per JDBC driver.
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Constructor Summary
Constructors Constructor Description JdbcDialectImpl()
JdbcDialectImpl(Connection connection)
Creates a JdbcDialectImpl.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
allowsAs()
Returns whether the SQL dialect allows "AS" in the FROM clause.boolean
allowsCompoundCountDistinct()
Returns whether this Dialect allows multiple arguments to theCOUNT(DISTINCT ...) aggregate function, for example
SELECT COUNT(DISTINCT x, y) FROM t
boolean
allowsCountDistinct()
Returns whether this Dialect supports distinct aggregations.boolean
allowsCountDistinctWithOtherAggs()
Returns whether this Dialect supports distinct aggregations with other aggregations in the same query.boolean
allowsDdl()
Returns whether this dialect supports common SQL Data Definition Language (DDL) statements such asCREATE TABLE
andDROP INDEX
.boolean
allowsDialectSharing()
Returns whether this Dialect object can be used for all connections from the same data source.boolean
allowsFromQuery()
Returns whether this Dialect allows a subquery in the from clause, for exampleSELECT * FROM (SELECT * FROM t) AS x
boolean
allowsJoinOn()
Returns whether this dialect supports "ANSI-style JOIN syntax",FROM leftTable JOIN rightTable ON conditon
.boolean
allowsMultipleCountDistinct()
Returns whether this Dialect supports more than one distinct aggregation in the same query.boolean
allowsMultipleDistinctSqlMeasures()
Returns whether this Dialect has performant support of distinct SQL measures in the same query.boolean
allowsOrderByAlias()
Returns true if aliases defined in the SELECT clause can be used as expressions in the ORDER BY clause.boolean
allowsRegularExpressionInWhereClause()
Informs Mondrian if the dialect supports regular expressions when creating the 'where' or the 'having' clause.boolean
allowsSelectNotInGroupBy()
Returns whether the database currently permits queries to include in the SELECT clause expressions that are not listed in the GROUP BY clause.void
appendHintsAfterFromClause(StringBuilder buf, Map<String,String> hints)
Assembles and returns a string containing any hints that should be appended after the FROM clause in a SELECT statement, based on any hints provided.String
caseWhenElse(String cond, String thenExpr, String elseExpr)
Generates a conditional statement in this dialect's syntax.protected List<StatisticsProvider>
computeStatisticsProviders()
protected String
deduceIdentifierQuoteString(DatabaseMetaData databaseMetaData)
protected int
deduceMaxColumnNameLength(DatabaseMetaData databaseMetaData)
protected String
deduceProductName(DatabaseMetaData databaseMetaData)
protected String
deduceProductVersion(DatabaseMetaData databaseMetaData)
protected boolean
deduceReadOnly(DatabaseMetaData databaseMetaData)
protected Set<List<Integer>>
deduceSupportedResultSetStyles(DatabaseMetaData databaseMetaData)
protected boolean
deduceSupportsSelectNotInGroupBy(Connection conn)
Detects whether the database is configured to permit queries that include columns in the SELECT that are not also in the GROUP BY.String
extractEmbeddedFlags(String javaRegex, String[][] mapping, StringBuilder dialectFlags)
Helper method to extract and map Java regular expression embedded flags expressions to dialect specific flags.String
generateCountExpression(String exp)
Some databases, like Greenplum, don't include nulls as part of the results of a COUNT sql call.String
generateInline(List<String> columnNames, List<String> columnTypes, List<String[]> valueList)
Generates a SQL statement to represent an inline dataset.String
generateInlineForAnsi(String alias, List<String> columnNames, List<String> columnTypes, List<String[]> valueList, boolean cast)
Generates inline values list using ANSI 'VALUES' syntax.protected String
generateInlineGeneric(List<String> columnNames, List<String> columnTypes, List<String[]> valueList, String fromClause, boolean cast)
Generic algorithm to generate inline values list, using an optional FROM clause, specified by the caller of this method, appropriate to the dialect of SQL.protected String
generateOrderByNulls(String expr, boolean ascending, boolean collateNullsLast)
Generates SQL to force null values to collate last.protected String
generateOrderByNullsAnsi(String expr, boolean ascending, boolean collateNullsLast)
Implementation for thegenerateOrderByNulls(java.lang.String, boolean, boolean)
method that uses the ANSI syntax "expr direction NULLS LAST" and "expr direction NULLS FIRST".String
generateOrderItem(String expr, boolean nullable, boolean ascending, boolean collateNullsLast)
Generates an item for an ORDER BY clause, sorting in the required direction, and ensuring that NULL values collate either before or after all non-NULL values, depending on thecollateNullsLast
parameter.String
generateRegularExpression(String source, String javaRegExp)
Must generate a String representing a regular expression match operation between a string literal and a Java regular expression.Dialect.DatabaseProduct
getDatabaseProduct()
Returns the database for this Dialect, orDialect.DatabaseProduct.UNKNOWN
if the database is not a common database.int
getMaxColumnNameLength()
Returns the maximum length of the name of a database column or query alias allowed by this dialect.static Dialect.DatabaseProduct
getProduct(String productName, String productVersion)
Converts a product name and version (per the JDBC driver) into a product enumeration.String
getQuoteIdentifierString()
Returns the character which is used to quote identifiers, or null if quoting is not supported.List<StatisticsProvider>
getStatisticsProviders()
Returns a list of statistics providers for this dialect.SqlStatement.Type
getType(ResultSetMetaData metaData, int columnIndex)
Chooses the most appropriate type for accessing the values of a column in a result set for a dialect.protected static boolean
isDatabase(Dialect.DatabaseProduct databaseProduct, Connection connection)
Helper method to determine if a connection would work with a given database product.boolean
needsExponent(Object value, String valueString)
If Double values need to include additional exponent in its string represenation.void
quote(StringBuilder buf, Object value, Dialect.Datatype datatype)
Appends to a buffer a value quoted for its type.void
quoteBooleanLiteral(StringBuilder buf, String value)
Appends to a buffer a boolean literal.void
quoteDateLiteral(StringBuilder buf, String value)
Appends to a buffer a date literal.protected void
quoteDateLiteral(StringBuilder buf, String value, Date date)
Helper method forquoteDateLiteral(StringBuilder, String)
.String
quoteIdentifier(String val)
Encloses an identifier in quotation marks appropriate for this Dialect.void
quoteIdentifier(StringBuilder buf, String... names)
Appends to a buffer a list of identifiers, quoted appropriately for this Dialect.String
quoteIdentifier(String qual, String name)
Encloses an identifier in quotation marks appropriate for the current SQL dialect.void
quoteIdentifier(String val, StringBuilder buf)
Appends to a buffer an identifier, quoted appropriately for this Dialect.void
quoteNumericLiteral(StringBuilder buf, String value)
Appends to a buffer a numeric literal.void
quoteStringLiteral(StringBuilder buf, String s)
Appends to a buffer a single-quoted SQL string.void
quoteTimeLiteral(StringBuilder buf, String value)
Appends to a buffer a time literal.void
quoteTimestampLiteral(StringBuilder buf, String value)
Appends to a buffer a timestamp literal.protected void
quoteTimestampLiteral(StringBuilder buf, String value, Timestamp timestamp)
boolean
requiresAliasForFromQuery()
Returns whether this Dialect requires subqueries in the FROM clause to have an alias.boolean
requiresGroupByAlias()
Returns true if this Dialect can include expressions in the GROUP BY clause only by adding an expression to the SELECT clause and using its alias.boolean
requiresHavingAlias()
Returns true if this Dialect can include expressions in the HAVING clause only by adding an expression to the SELECT clause and using its alias.boolean
requiresOrderByAlias()
Returns true if this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias.boolean
requiresUnionOrderByExprToBeInSelectClause()
Returns true if this dialect allows an expression in the ORDER BY clause of a UNION (or other set operation) query only if it occurs in the SELECT clause.boolean
requiresUnionOrderByOrdinal()
Returns true if this dialect allows only integers in the ORDER BY clause of a UNION (or other set operation) query.boolean
supportsGroupByExpressions()
Returns whether this Dialect supports expressions in the GROUP BY clause.boolean
supportsGroupingSets()
Returns whether this Dialect allows the GROUPING SETS construct in the GROUP BY clause.boolean
supportsMultiValueInExpr()
Returns true if this dialect supports multi-value IN expressions.boolean
supportsResultSetConcurrency(int type, int concurrency)
Returns whether this Dialect supports the given concurrency type in combination with the given result set type.boolean
supportsUnlimitedValueList()
Returns whether this Dialect places no limit on the number of rows which can appear as elements of an IN or VALUES expression.String
toString()
String
toUpper(String expr)
Converts an expression to upper case.
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Field Detail
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productVersion
protected final String productVersion
Product version per JDBC driver.
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permitsSelectNotInGroupBy
protected boolean permitsSelectNotInGroupBy
Indicates whether the database allows selection of columns not listed in the group by clause.
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databaseProduct
protected final Dialect.DatabaseProduct databaseProduct
Major database product (or null if product is not a common one)
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Constructor Detail
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JdbcDialectImpl
public JdbcDialectImpl(Connection connection) throws SQLException
Creates a JdbcDialectImpl.To prevent connection leaks, this constructor does not hold a reference to the connection after the call returns. It makes a copy of everything useful during the call. Derived classes must do the same.
- Parameters:
connection
- Connection- Throws:
SQLException
- on error
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JdbcDialectImpl
public JdbcDialectImpl()
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Method Detail
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getDatabaseProduct
public Dialect.DatabaseProduct getDatabaseProduct()
Description copied from interface:Dialect
Returns the database for this Dialect, orDialect.DatabaseProduct.UNKNOWN
if the database is not a common database.- Specified by:
getDatabaseProduct
in interfaceDialect
- Returns:
- Database
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appendHintsAfterFromClause
public void appendHintsAfterFromClause(StringBuilder buf, Map<String,String> hints)
Description copied from interface:Dialect
Assembles and returns a string containing any hints that should be appended after the FROM clause in a SELECT statement, based on any hints provided. Any unrecognized or unsupported hints will be ignored.- Specified by:
appendHintsAfterFromClause
in interfaceDialect
- Parameters:
buf
- The Stringbuffer to which the dialect-specific syntax for any relevant table hints may be appended. Must not be null.hints
- A map of table hints provided in the schema definition
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allowsDialectSharing
public boolean allowsDialectSharing()
Description copied from interface:Dialect
Returns whether this Dialect object can be used for all connections from the same data source.The default implementation returns
true
, and this allows dialects to be cached and reused in environments where connections are allocated from a pool based on the same data source.Data sources are deemed 'equal' by the same criteria used by Java collections, namely the
Object.equals(Object)
andObject.hashCode()
methods.- Specified by:
allowsDialectSharing
in interfaceDialect
- Returns:
- Whether this dialect can be used for other connections created from the same data source
- See Also:
DialectFactory.createDialect(javax.sql.DataSource, java.sql.Connection)
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deduceMaxColumnNameLength
protected int deduceMaxColumnNameLength(DatabaseMetaData databaseMetaData)
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deduceReadOnly
protected boolean deduceReadOnly(DatabaseMetaData databaseMetaData)
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deduceProductName
protected String deduceProductName(DatabaseMetaData databaseMetaData)
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deduceIdentifierQuoteString
protected String deduceIdentifierQuoteString(DatabaseMetaData databaseMetaData)
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deduceProductVersion
protected String deduceProductVersion(DatabaseMetaData databaseMetaData)
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deduceSupportedResultSetStyles
protected Set<List<Integer>> deduceSupportedResultSetStyles(DatabaseMetaData databaseMetaData)
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deduceSupportsSelectNotInGroupBy
protected boolean deduceSupportsSelectNotInGroupBy(Connection conn) throws SQLException
Detects whether the database is configured to permit queries that include columns in the SELECT that are not also in the GROUP BY. MySQL is an example of one that does, though this is configurable.
The expectation is that this will not change while Mondrian is running, though some databases (MySQL) allow changing it on the fly.
- Parameters:
conn
- The database connection- Returns:
- Whether the feature is enabled.
- Throws:
SQLException
- on error
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toUpper
public String toUpper(String expr)
Description copied from interface:Dialect
Converts an expression to upper case.For example, for MySQL,
toUpper("foo.bar")
returns"UPPER(foo.bar)"
.
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caseWhenElse
public String caseWhenElse(String cond, String thenExpr, String elseExpr)
Description copied from interface:Dialect
Generates a conditional statement in this dialect's syntax.For example,
caseWhenElse("b", "1", "0")
returns"case when b then 1 else 0 end"
on Oracle,"Iif(b, 1, 0)"
on Access.- Specified by:
caseWhenElse
in interfaceDialect
- Parameters:
cond
- Predicate expressionthenExpr
- Expression if condition is trueelseExpr
- Expression if condition is false- Returns:
- Conditional expression
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quoteIdentifier
public String quoteIdentifier(String val)
Description copied from interface:Dialect
Encloses an identifier in quotation marks appropriate for this Dialect.For example,
quoteIdentifier("emp")
yields a string containing"emp"
in Oracle, and a string containing[emp]
in Access.- Specified by:
quoteIdentifier
in interfaceDialect
- Parameters:
val
- Identifier- Returns:
- Quoted identifier
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quoteIdentifier
public void quoteIdentifier(String val, StringBuilder buf)
Description copied from interface:Dialect
Appends to a buffer an identifier, quoted appropriately for this Dialect.- Specified by:
quoteIdentifier
in interfaceDialect
- Parameters:
val
- identifier to quote (must not be null).buf
- Buffer
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quoteIdentifier
public String quoteIdentifier(String qual, String name)
Description copied from interface:Dialect
Encloses an identifier in quotation marks appropriate for the current SQL dialect. For example, in Oracle, where the identifiers are quoted using double-quotes,quoteIdentifier("schema","table")
yields a string containing"schema"."table"
.- Specified by:
quoteIdentifier
in interfaceDialect
- Parameters:
qual
- Qualifier. If it is not null,"qual".
is prepended.name
- Name to be quoted.- Returns:
- Quoted identifier
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quoteIdentifier
public void quoteIdentifier(StringBuilder buf, String... names)
Description copied from interface:Dialect
Appends to a buffer a list of identifiers, quoted appropriately for this Dialect.Names in the list may be null, but there must be at least one non-null name in the list.
- Specified by:
quoteIdentifier
in interfaceDialect
- Parameters:
buf
- Buffernames
- List of names to be quoted
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getQuoteIdentifierString
public String getQuoteIdentifierString()
Description copied from interface:Dialect
Returns the character which is used to quote identifiers, or null if quoting is not supported.- Specified by:
getQuoteIdentifierString
in interfaceDialect
- Returns:
- identifier quote
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quoteStringLiteral
public void quoteStringLiteral(StringBuilder buf, String s)
Description copied from interface:Dialect
Appends to a buffer a single-quoted SQL string.For example, in the default dialect,
quoteStringLiteral(buf, "Can't")
appends "'Can''t'
" tobuf
.- Specified by:
quoteStringLiteral
in interfaceDialect
- Parameters:
buf
- Buffer to append tos
- Literal
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quoteNumericLiteral
public void quoteNumericLiteral(StringBuilder buf, String value)
Description copied from interface:Dialect
Appends to a buffer a numeric literal.In the default dialect, numeric literals are printed as is.
- Specified by:
quoteNumericLiteral
in interfaceDialect
- Parameters:
buf
- Buffer to append tovalue
- Literal
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quoteBooleanLiteral
public void quoteBooleanLiteral(StringBuilder buf, String value)
Description copied from interface:Dialect
Appends to a buffer a boolean literal.In the default dialect, boolean literals are printed as is.
- Specified by:
quoteBooleanLiteral
in interfaceDialect
- Parameters:
buf
- Buffer to append tovalue
- Literal
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quoteDateLiteral
public void quoteDateLiteral(StringBuilder buf, String value)
Description copied from interface:Dialect
Appends to a buffer a date literal.For example, in the default dialect,
quoteStringLiteral(buf, "1969-03-17")
appendsDATE '1969-03-17'
.- Specified by:
quoteDateLiteral
in interfaceDialect
- Parameters:
buf
- Buffer to append tovalue
- Literal
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quoteDateLiteral
protected void quoteDateLiteral(StringBuilder buf, String value, Date date)
Helper method forquoteDateLiteral(StringBuilder, String)
.- Parameters:
buf
- Buffer to append tovalue
- Value as stringdate
- Value as date
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quoteTimeLiteral
public void quoteTimeLiteral(StringBuilder buf, String value)
Description copied from interface:Dialect
Appends to a buffer a time literal.For example, in the default dialect,
quoteStringLiteral(buf, "12:34:56")
appendsTIME '12:34:56'
.- Specified by:
quoteTimeLiteral
in interfaceDialect
- Parameters:
buf
- Buffer to append tovalue
- Literal
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quoteTimestampLiteral
public void quoteTimestampLiteral(StringBuilder buf, String value)
Description copied from interface:Dialect
Appends to a buffer a timestamp literal.For example, in the default dialect,
quoteStringLiteral(buf, "1969-03-17 12:34:56")
appendsTIMESTAMP '1969-03-17 12:34:56'
.- Specified by:
quoteTimestampLiteral
in interfaceDialect
- Parameters:
buf
- Buffer to append tovalue
- Literal
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quoteTimestampLiteral
protected void quoteTimestampLiteral(StringBuilder buf, String value, Timestamp timestamp)
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requiresAliasForFromQuery
public boolean requiresAliasForFromQuery()
Description copied from interface:Dialect
Returns whether this Dialect requires subqueries in the FROM clause to have an alias.- Specified by:
requiresAliasForFromQuery
in interfaceDialect
- Returns:
- whether dialewct requires subqueries to have an alias
- See Also:
Dialect.allowsFromQuery()
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allowsAs
public boolean allowsAs()
Description copied from interface:Dialect
Returns whether the SQL dialect allows "AS" in the FROM clause. If so, "SELECT * FROM t AS alias" is a valid query.
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allowsFromQuery
public boolean allowsFromQuery()
Description copied from interface:Dialect
Returns whether this Dialect allows a subquery in the from clause, for exampleSELECT * FROM (SELECT * FROM t) AS x
- Specified by:
allowsFromQuery
in interfaceDialect
- Returns:
- whether Dialect allows subquery in FROM clause
- See Also:
Dialect.requiresAliasForFromQuery()
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allowsCompoundCountDistinct
public boolean allowsCompoundCountDistinct()
Description copied from interface:Dialect
Returns whether this Dialect allows multiple arguments to theCOUNT(DISTINCT ...) aggregate function, for example
SELECT COUNT(DISTINCT x, y) FROM t
- Specified by:
allowsCompoundCountDistinct
in interfaceDialect
- Returns:
- whether Dialect allows multiple arguments to COUNT DISTINCT
- See Also:
Dialect.allowsCountDistinct()
,Dialect.allowsMultipleCountDistinct()
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allowsCountDistinct
public boolean allowsCountDistinct()
Description copied from interface:Dialect
Returns whether this Dialect supports distinct aggregations.For example, Access does not allow
select count(distinct x) from t
- Specified by:
allowsCountDistinct
in interfaceDialect
- Returns:
- whether Dialect allows COUNT DISTINCT
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allowsMultipleCountDistinct
public boolean allowsMultipleCountDistinct()
Description copied from interface:Dialect
Returns whether this Dialect supports more than one distinct aggregation in the same query.In Derby 10.1,
select couunt(distinct x) from t
select couunt(distinct x), count(distinct y) from t
- Specified by:
allowsMultipleCountDistinct
in interfaceDialect
- Returns:
- whether this Dialect supports more than one distinct aggregation in the same query
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allowsMultipleDistinctSqlMeasures
public boolean allowsMultipleDistinctSqlMeasures()
Description copied from interface:Dialect
Returns whether this Dialect has performant support of distinct SQL measures in the same query.- Specified by:
allowsMultipleDistinctSqlMeasures
in interfaceDialect
- Returns:
- whether this dialect supports multiple count(distinct subquery) measures in one query.
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allowsCountDistinctWithOtherAggs
public boolean allowsCountDistinctWithOtherAggs()
Description copied from interface:Dialect
Returns whether this Dialect supports distinct aggregations with other aggregations in the same query. This may be enabled for performance reasons (Vertica)- Specified by:
allowsCountDistinctWithOtherAggs
in interfaceDialect
- Returns:
- whether this Dialect supports more than one distinct aggregation in the same query
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generateInline
public String generateInline(List<String> columnNames, List<String> columnTypes, List<String[]> valueList)
Description copied from interface:Dialect
Generates a SQL statement to represent an inline dataset.For example, for Oracle, generates
SELECT 1 AS FOO, 'a' AS BAR FROM dual UNION ALL SELECT 2 AS FOO, 'b' AS BAR FROM dual
For ANSI SQL, generates:
VALUES (1, 'a'), (2, 'b')
- Specified by:
generateInline
in interfaceDialect
- Parameters:
columnNames
- List of column namescolumnTypes
- List of column types ("String" or "Numeric")valueList
- List of rows values- Returns:
- SQL string
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generateInlineGeneric
protected String generateInlineGeneric(List<String> columnNames, List<String> columnTypes, List<String[]> valueList, String fromClause, boolean cast)
Generic algorithm to generate inline values list, using an optional FROM clause, specified by the caller of this method, appropriate to the dialect of SQL.- Parameters:
columnNames
- Column namescolumnTypes
- Column typesvalueList
- List rowsfromClause
- FROM clause, or nullcast
- Whether to cast the values in the first row- Returns:
- Expression that returns the given values
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generateInlineForAnsi
public String generateInlineForAnsi(String alias, List<String> columnNames, List<String> columnTypes, List<String[]> valueList, boolean cast)
Generates inline values list using ANSI 'VALUES' syntax. For example,SELECT * FROM (VALUES (1, 'a'), (2, 'b')) AS t(x, y)
If NULL values are present, we use a CAST to ensure that they have the same type as other columns:
SELECT * FROM (VALUES (1, 'a'), (2, CASE(NULL AS VARCHAR(1)))) AS t(x, y)
This syntax is known to work on Derby, but not Oracle 10 or Access.
- Parameters:
alias
- Table aliascolumnNames
- Column namescolumnTypes
- Column typesvalueList
- List rowscast
- Whether to generate casts- Returns:
- Expression that returns the given values
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needsExponent
public boolean needsExponent(Object value, String valueString)
Description copied from interface:Dialect
If Double values need to include additional exponent in its string represenation. This is to make sure that Double literals will be interpreted as doubles by LucidDB.- Specified by:
needsExponent
in interfaceDialect
- Parameters:
value
- Double value to generate string forvalueString
- java string representation for this value.- Returns:
- whether an additional exponent "E0" needs to be appended
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quote
public void quote(StringBuilder buf, Object value, Dialect.Datatype datatype)
Description copied from interface:Dialect
Appends to a buffer a value quoted for its type.
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allowsDdl
public boolean allowsDdl()
Description copied from interface:Dialect
Returns whether this dialect supports common SQL Data Definition Language (DDL) statements such asCREATE TABLE
andDROP INDEX
.Access seems to allow DDL iff the .mdb file is writeable.
- Specified by:
allowsDdl
in interfaceDialect
- Returns:
- whether this Dialect supports DDL
- See Also:
DatabaseMetaData.isReadOnly()
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generateOrderItem
public String generateOrderItem(String expr, boolean nullable, boolean ascending, boolean collateNullsLast)
Description copied from interface:Dialect
Generates an item for an ORDER BY clause, sorting in the required direction, and ensuring that NULL values collate either before or after all non-NULL values, depending on thecollateNullsLast
parameter.- Specified by:
generateOrderItem
in interfaceDialect
- Parameters:
expr
- Expressionnullable
- Whether expression may have NULL valuesascending
- Whether to sort expression ascendingcollateNullsLast
- Whether the null values should be sorted first or last.- Returns:
- Expression modified so that NULL values collate last
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generateOrderByNulls
protected String generateOrderByNulls(String expr, boolean ascending, boolean collateNullsLast)
Generates SQL to force null values to collate last.This default implementation makes use of the ANSI SQL 1999 CASE-WHEN-THEN-ELSE in conjunction with IS NULL syntax. The resulting SQL will look something like this:
CASE WHEN "expr" IS NULL THEN 0 ELSE 1 END
You can override this method for a particular database to use something more efficient, like ISNULL().
ANSI SQL provides the syntax "ASC/DESC NULLS LAST" and "ASC/DESC NULLS FIRST". If your database supports the ANSI syntax, implement this method by calling
generateOrderByNullsAnsi(java.lang.String, boolean, boolean)
.This method is only called from
generateOrderItem(String, boolean, boolean, boolean)
. Some dialects override that method and therefore never call this method.- Parameters:
expr
- Expression.ascending
- Whether ascending.collateNullsLast
- Whether nulls should appear first or last.- Returns:
- Expression to force null values to collate last or first.
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generateOrderByNullsAnsi
protected final String generateOrderByNullsAnsi(String expr, boolean ascending, boolean collateNullsLast)
Implementation for thegenerateOrderByNulls(java.lang.String, boolean, boolean)
method that uses the ANSI syntax "expr direction NULLS LAST" and "expr direction NULLS FIRST".- Parameters:
expr
- Expressionascending
- Whether ascendingcollateNullsLast
- Whether nulls should appear first or last.- Returns:
- Expression "expr direction NULLS LAST"
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supportsGroupByExpressions
public boolean supportsGroupByExpressions()
Description copied from interface:Dialect
Returns whether this Dialect supports expressions in the GROUP BY clause. Derby/Cloudscape and Infobright do not.- Specified by:
supportsGroupByExpressions
in interfaceDialect
- Returns:
- Whether this Dialect allows expressions in the GROUP BY clause
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allowsSelectNotInGroupBy
public boolean allowsSelectNotInGroupBy()
Description copied from interface:Dialect
Returns whether the database currently permits queries to include in the SELECT clause expressions that are not listed in the GROUP BY clause. The SQL standard allows this if the database can deduce that the expression is functionally dependent on columns in the GROUP BY clause.For example,
SELECT empno, first_name || ' ' || last_name FROM emps GROUP BY empno
is valid becauseempno
is the primary key of theemps
table, and therefore all columns are dependent on it. For a given value ofempno
,first_name || ' ' || last_name
has a unique value.Most databases do not, MySQL is an example of one that does (if the functioality is enabled).
- Specified by:
allowsSelectNotInGroupBy
in interfaceDialect
- Returns:
- Whether this Dialect allows SELECT clauses to contain columns that are not in the GROUP BY clause
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allowsJoinOn
public boolean allowsJoinOn()
Description copied from interface:Dialect
Returns whether this dialect supports "ANSI-style JOIN syntax",FROM leftTable JOIN rightTable ON conditon
.- Specified by:
allowsJoinOn
in interfaceDialect
- Returns:
- Whether this dialect supports FROM-JOIN-ON syntax.
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supportsGroupingSets
public boolean supportsGroupingSets()
Description copied from interface:Dialect
Returns whether this Dialect allows the GROUPING SETS construct in the GROUP BY clause. Currently Greenplum, IBM DB2, Oracle, and Teradata.- Specified by:
supportsGroupingSets
in interfaceDialect
- Returns:
- Whether this Dialect allows GROUPING SETS clause
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supportsUnlimitedValueList
public boolean supportsUnlimitedValueList()
Description copied from interface:Dialect
Returns whether this Dialect places no limit on the number of rows which can appear as elements of an IN or VALUES expression.- Specified by:
supportsUnlimitedValueList
in interfaceDialect
- Returns:
- whether value list length is unlimited
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requiresGroupByAlias
public boolean requiresGroupByAlias()
Description copied from interface:Dialect
Returns true if this Dialect can include expressions in the GROUP BY clause only by adding an expression to the SELECT clause and using its alias.For example, in such a dialect,
SELECT x, x FROM t GROUP BY x
SELECT x AS a, x AS b FROM t ORDER BY a, b
Infobright is the only such dialect.
- Specified by:
requiresGroupByAlias
in interfaceDialect
- Returns:
- Whether this Dialect can include expressions in the GROUP BY clause only by adding an expression to the SELECT clause and using its alias
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requiresOrderByAlias
public boolean requiresOrderByAlias()
Description copied from interface:Dialect
Returns true if this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias.For example, in such a dialect,
SELECT x FROM t ORDER BY x + y
SELECT x, x + y AS z FROM t ORDER BY z
MySQL, DB2 and Ingres are examples of such dialects.
- Specified by:
requiresOrderByAlias
in interfaceDialect
- Returns:
- Whether this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias
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requiresHavingAlias
public boolean requiresHavingAlias()
Description copied from interface:Dialect
Returns true if this Dialect can include expressions in the HAVING clause only by adding an expression to the SELECT clause and using its alias.For example, in such a dialect,
SELECT CONCAT(x) as foo FROM t HAVING CONCAT(x) LIKE "%"
SELECT CONCAT(x) as foo FROM t HAVING foo LIKE "%"
MySQL is an example of such dialects.
- Specified by:
requiresHavingAlias
in interfaceDialect
- Returns:
- Whether this Dialect can include expressions in the HAVING clause only by adding an expression to the SELECT clause and using its alias
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allowsOrderByAlias
public boolean allowsOrderByAlias()
Description copied from interface:Dialect
Returns true if aliases defined in the SELECT clause can be used as expressions in the ORDER BY clause.For example, in such a dialect,
SELECT x, x + y AS z FROM t ORDER BY z
MySQL, DB2 and Ingres are examples of dialects where this is true; Access is a dialect where this is false.
- Specified by:
allowsOrderByAlias
in interfaceDialect
- Returns:
- Whether aliases defined in the SELECT clause can be used as expressions in the ORDER BY clause.
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requiresUnionOrderByOrdinal
public boolean requiresUnionOrderByOrdinal()
Description copied from interface:Dialect
Returns true if this dialect allows only integers in the ORDER BY clause of a UNION (or other set operation) query.For example,
SELECT x, y + z FROM t
is allowed but
UNION ALL
SELECT x, y + z FROM t
ORDER BY 1, 2SELECT x, y, z FROM t
is not.
UNION ALL
SELECT x, y, z FROM t
ORDER BY xTeradata is an example of a dialect with this restriction.
- Specified by:
requiresUnionOrderByOrdinal
in interfaceDialect
- Returns:
- whether this dialect allows only integers in the ORDER BY clause of a UNION (or other set operation) query
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requiresUnionOrderByExprToBeInSelectClause
public boolean requiresUnionOrderByExprToBeInSelectClause()
Description copied from interface:Dialect
Returns true if this dialect allows an expression in the ORDER BY clause of a UNION (or other set operation) query only if it occurs in the SELECT clause.For example,
SELECT x, y + z FROM t
is allowed but
UNION ALL
SELECT x, y + z FROM t
ORDER BY y + zSELECT x, y, z FROM t
UNION ALL
SELECT x, y, z FROM t
ORDER BY y + zSELECT x, y, z FROM t ORDER BY y + z
is not.Access is an example of a dialect with this restriction.
- Specified by:
requiresUnionOrderByExprToBeInSelectClause
in interfaceDialect
- Returns:
- whether this dialect allows an expression in the ORDER BY clause of a UNION (or other set operation) query only if it occurs in the SELECT clause
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supportsMultiValueInExpr
public boolean supportsMultiValueInExpr()
Description copied from interface:Dialect
Returns true if this dialect supports multi-value IN expressions. E.g.,WHERE (col1, col2) IN ((val1a, val2a), (val1b, val2b))
- Specified by:
supportsMultiValueInExpr
in interfaceDialect
- Returns:
- true if the dialect supports multi-value IN expressions
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supportsResultSetConcurrency
public boolean supportsResultSetConcurrency(int type, int concurrency)
Description copied from interface:Dialect
Returns whether this Dialect supports the given concurrency type in combination with the given result set type.The result is similar to
DatabaseMetaData.supportsResultSetConcurrency(int, int)
, except that the JdbcOdbc bridge in JDK 1.6 overstates its abilities. See bug 1690406.- Specified by:
supportsResultSetConcurrency
in interfaceDialect
- Parameters:
type
- defined inResultSet
concurrency
- type defined inResultSet
- Returns:
true
if so;false
otherwise
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getMaxColumnNameLength
public int getMaxColumnNameLength()
Description copied from interface:Dialect
Returns the maximum length of the name of a database column or query alias allowed by this dialect.- Specified by:
getMaxColumnNameLength
in interfaceDialect
- Returns:
- maximum number of characters in a column name
- See Also:
DatabaseMetaData.getMaxColumnNameLength()
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allowsRegularExpressionInWhereClause
public boolean allowsRegularExpressionInWhereClause()
Description copied from interface:Dialect
Informs Mondrian if the dialect supports regular expressions when creating the 'where' or the 'having' clause.- Specified by:
allowsRegularExpressionInWhereClause
in interfaceDialect
- Returns:
- True if regular expressions are supported.
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generateCountExpression
public String generateCountExpression(String exp)
Description copied from interface:Dialect
Some databases, like Greenplum, don't include nulls as part of the results of a COUNT sql call. This allows dialects to wrap the count expression in something before it is used in the query.- Specified by:
generateCountExpression
in interfaceDialect
- Parameters:
exp
- The expression to wrap.- Returns:
- A valid expression to use for a count operation.
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generateRegularExpression
public String generateRegularExpression(String source, String javaRegExp)
Description copied from interface:Dialect
Must generate a String representing a regular expression match operation between a string literal and a Java regular expression. The string literal might be a column identifier or some other identifier, but the implementation must presume that it is already escaped and fit for use. The regular expression is not escaped and must be adapted to the proper dialect rules.Postgres / Greenplum example:
generateRegularExpression( "'foodmart'.'customer_name'", "(?i).*oo.*") -> 'foodmart'.'customer_name' ~ "(?i).*oo.*"
Oracle example:
generateRegularExpression( "'foodmart'.'customer_name'", ".*oo.*") -> REGEXP_LIKE('foodmart'.'customer_name', ".*oo.*")
Dialects are allowed to return null if the dialect cannot convert that particular regular expression into something that the database would support.
- Specified by:
generateRegularExpression
in interfaceDialect
- Parameters:
source
- A String identifying the column to match against.javaRegExp
- A Java regular expression to match against.- Returns:
- A dialect specific matching operation, or null if the dialect cannot convert that particular regular expression into something that the database would support.
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getStatisticsProviders
public List<StatisticsProvider> getStatisticsProviders()
Description copied from interface:Dialect
Returns a list of statistics providers for this dialect.The default implementation looks for the value of the property
mondrian.statistics.providers.PRODUCT
where product is the current dialect's product name (for example "MYSQL"). If that property has no value, looks at the propertymondrian.statistics.providers
. The property value should be a comma-separated list of names of classes that implement theStatisticsProvider
interface. For each statistic required, Mondrian will call the method each statistics provider in turn, until one of them returns a non-negative value.- Specified by:
getStatisticsProviders
in interfaceDialect
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getType
public SqlStatement.Type getType(ResultSetMetaData metaData, int columnIndex) throws SQLException
Description copied from interface:Dialect
Chooses the most appropriate type for accessing the values of a column in a result set for a dialect.
Dialect-specific nuances involving type representation should be encapsulated in implementing methods. For example, if a dialect has implicit rules involving scale or precision, they should be handled within this method so the client can simply retrieve the "best fit" SqlStatement.Type for the column.
- Specified by:
getType
in interfaceDialect
- Parameters:
metaData
- Results set metadatacolumnIndex
- Column ordinal (0-based)- Returns:
- the most appropriate SqlStatement.Type for the column
- Throws:
SQLException
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computeStatisticsProviders
protected List<StatisticsProvider> computeStatisticsProviders()
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getProduct
public static Dialect.DatabaseProduct getProduct(String productName, String productVersion)
Converts a product name and version (per the JDBC driver) into a product enumeration.- Parameters:
productName
- Product nameproductVersion
- Product version- Returns:
- database product
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isDatabase
protected static boolean isDatabase(Dialect.DatabaseProduct databaseProduct, Connection connection)
Helper method to determine if a connection would work with a given database product. This can be used to differenciate between databases which use the same driver as others.It will first try to use
DatabaseMetaData.getDatabaseProductName()
and match the name ofDialect.DatabaseProduct
passed as an argument.If that fails, it will try to execute
select version();
and obtains some information directly from the server.- Parameters:
databaseProduct
- Database product instanceconnection
- SQL connection- Returns:
- true if a match was found. false otherwise.
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extractEmbeddedFlags
public String extractEmbeddedFlags(String javaRegex, String[][] mapping, StringBuilder dialectFlags)
Helper method to extract and map Java regular expression embedded flags expressions to dialect specific flags. All dialects will map the case insensitive expression (?i) to i. However, Vertica maps the dotall flag (?s) to n. For example, on Vertica, a regular expression like: "(?is).*Hello World.*" will return: ".*Hello World.*" with dialect flags: "in"- Parameters:
origExp
- Java regular expressionmapping
- 2D String array of supported Java flags that can be mapped to a dialect specific flag.dialectFlags
- Returns the dialect specific flags in the input regular expression.- Returns:
- Regular expression with the Java flags removed.
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