Package uk.ac.starlink.table.jdbc
Class JDBCStarTable
java.lang.Object
uk.ac.starlink.table.AbstractStarTable
uk.ac.starlink.table.jdbc.JDBCStarTable
- All Implemented Interfaces:
Closeable
,AutoCloseable
,StarTable
A StarTable implementation based on the results of an SQL query
on a JDBC table.
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Constructor Summary
ConstructorsConstructorDescriptionJDBCStarTable
(Connector connx, String sql) Constructs a StarTable representing the data returned by an SQL query using a JDBC connections from a given source, with sequential access only.JDBCStarTable
(Connector connx, String sql, boolean isRandom) Constructs a StarTable representing the data returned by an SQL query using JDBC connections from a given source, optionally providing random access. -
Method Summary
Modifier and TypeMethodDescriptiongetCell
(long lrow, int icol) The AbstractStarTable implementation of this method throws an UnsupportedOperationException, since unless otherwise provided there is no random access.Goes through the table columns (ColumnInfo objects) and picks out all the AuxData items which exist, generalising where necessary and returning a union of them in alphabetical order by name.int
Returns the number of columns in this table.getColumnInfo
(int icol) Returns the object describing the data in a given column.Returns a JDBC Connection that can supply the data for this table.Object[]
getRow
(long lrow) The AbstractStarTable implementation of this method constructs a row by repeated invocation ofAbstractStarTable.getCell(long, int)
.Returns an object which can provide random access to this table's data, if random access is implemented.long
Returns the number of rows in this table, if known.Returns an object which can iterate over all the rows in the table sequentially.getSql()
Returns the text of the SQL query used for this table.boolean
isRandom()
The AbstractStarTable implementation of this method returns false.void
Ensures that this table provides random access.Methods inherited from class uk.ac.starlink.table.AbstractStarTable
checkedLongToInt, close, getName, getParameters, getRowSplittable, getURL, setName, setParameters, setURL
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface uk.ac.starlink.table.StarTable
getParameterByName, setParameter
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Constructor Details
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JDBCStarTable
Constructs a StarTable representing the data returned by an SQL query using a JDBC connections from a given source, with sequential access only.- Parameters:
connx
- object which can supply JDBC connectionssql
- text of the SQL query- Throws:
SQLException
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JDBCStarTable
Constructs a StarTable representing the data returned by an SQL query using JDBC connections from a given source, optionally providing random access.This was initially written to take a
Connection
rather than aConnector
object, but it seems that there are limits to the number of ResultSets that can be simultaneously open on a Connection.- Parameters:
connx
- object which can supply JDBC connectionssql
- text of the SQL queryisRandom
- whether this table needs to provide random access or not (there are costs associated with this)- Throws:
SQLException
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Method Details
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getColumnInfo
Description copied from interface:StarTable
Returns the object describing the data in a given column.- Specified by:
getColumnInfo
in interfaceStarTable
- Specified by:
getColumnInfo
in classAbstractStarTable
- Parameters:
icol
- the column for which header information is required- Returns:
- a ValueInfo object for column icol
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getColumnAuxDataInfos
Description copied from class:AbstractStarTable
Goes through the table columns (ColumnInfo objects) and picks out all the AuxData items which exist, generalising where necessary and returning a union of them in alphabetical order by name. Subclasses should override this if they can do better, for instance providing an order for the keys.- Specified by:
getColumnAuxDataInfos
in interfaceStarTable
- Overrides:
getColumnAuxDataInfos
in classAbstractStarTable
- Returns:
- a list of all the auxiliary metadata ValueInfo items which in fact crop up in column metadata
- See Also:
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getColumnCount
public int getColumnCount()Description copied from interface:StarTable
Returns the number of columns in this table.- Specified by:
getColumnCount
in interfaceStarTable
- Specified by:
getColumnCount
in classAbstractStarTable
- Returns:
- the number of columns
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getRowCount
public long getRowCount()Description copied from interface:StarTable
Returns the number of rows in this table, if known. If the number of rows cannot be (easily) determined, a value of -1 will be returned.- Specified by:
getRowCount
in interfaceStarTable
- Specified by:
getRowCount
in classAbstractStarTable
- Returns:
- the number of rows, or -1
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setRandom
Ensures that this table provides random access. Following this call the isRandom method will return true. Calling this method multiple times is harmless.- Throws:
SQLException
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isRandom
public boolean isRandom()Description copied from class:AbstractStarTable
The AbstractStarTable implementation of this method returns false.- Specified by:
isRandom
in interfaceStarTable
- Overrides:
isRandom
in classAbstractStarTable
- Returns:
- true if table random access methods are available
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getCell
Description copied from class:AbstractStarTable
The AbstractStarTable implementation of this method throws an UnsupportedOperationException, since unless otherwise provided there is no random access.- Specified by:
getCell
in interfaceStarTable
- Overrides:
getCell
in classAbstractStarTable
- Parameters:
lrow
- the index of the cell's rowicol
- the index of the cell's column- Returns:
- the contents of this cell
- Throws:
IOException
- if there is an error reading the data
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getRow
Description copied from class:AbstractStarTable
The AbstractStarTable implementation of this method constructs a row by repeated invocation ofAbstractStarTable.getCell(long, int)
.- Specified by:
getRow
in interfaceStarTable
- Overrides:
getRow
in classAbstractStarTable
- Parameters:
lrow
- the index of the row to retrieve- Returns:
- an array of the objects in each cell in row irow
- Throws:
IOException
- if there is an error reading the data
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getRowAccess
Description copied from interface:StarTable
Returns an object which can provide random access to this table's data, if random access is implemented. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.- Specified by:
getRowAccess
in interfaceStarTable
- Overrides:
getRowAccess
in classAbstractStarTable
- Returns:
- new RowAccess
- Throws:
IOException
- if there is an error setting up access
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getRowSequence
Description copied from interface:StarTable
Returns an object which can iterate over all the rows in the table sequentially. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.- Specified by:
getRowSequence
in interfaceStarTable
- Specified by:
getRowSequence
in classAbstractStarTable
- Returns:
- new RowSequence
- Throws:
IOException
- if there is an error providing access
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getConnection
Returns a JDBC Connection that can supply the data for this table.- Returns:
- a JDBC Connection object
- Throws:
SQLException
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getSql
Returns the text of the SQL query used for this table.- Returns:
- the SQL query text
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