Package com.streambase.sb.operator

Interface TableAccessor

public interface TableAccessor

A handle for accessing a table. Retrieve an instance in an Operator via Operator.getTableAccessor(String).

Since:

7.2

Field Summary

Fields

Modifier and Type	Field	Description
static final String	QUERY_ARGUMENT_QUALIFIER	Query argument qualifier - "input"

Method Summary

Modifier and Type	Method	Description
Tuple	createRow()
Tuple	delete(Tuple pkey)	Delete a row in the table based on primary key.
List<Schema.Field>	getPrimaryKeyFields()	The fields from the schema which make up the primary key.
Schema	getSchema()	The schema for rows in this table.
void	insert(Tuple row)	Insert a new row into the table.
PreparedQuery	prepare(String predicate, Schema args)	Prepare an index-accessing query.
Tuple	readPrimary(Tuple pkey)	Read a row from the table by primary key.
Tuple	replace(Tuple row)	Replace a row in the table, or insert if there is no existing row with matching primary key.
long	size(boolean slowAndAccurate)	Return the number of rows in the table
void	truncate()	Truncate the table, by removing all rows

Field Details

QUERY_ARGUMENT_QUALIFIER

static final String QUERY_ARGUMENT_QUALIFIER

Query argument qualifier - "input"

See Also:

• Constant Field Values

Method Details

getSchema

Schema getSchema()

The schema for rows in this table.

Returns:

Table schema

getPrimaryKeyFields

List<Schema.Field> getPrimaryKeyFields()

The fields from the schema which make up the primary key.

Returns:

Primary key fields

createRow

Tuple createRow()

Returns:

a new row object suitable for adding to or querying from the table.

readPrimary

Tuple readPrimary(Tuple pkey)
           throws StreamBaseException

Read a row from the table by primary key. The row is read only, and valid until the table is modified.

Parameters:

pkey - row object with primary key material populated.

Returns:

The matching table row if any, or null.

Throws:

StreamBaseException - if the key is invalid

prepare

PreparedQuery prepare(String predicate,
 Schema args)
               throws StreamBaseException

Prepare an index-accessing query.

Parameters:

predicate - Predicate which may reference table fields and fields present in args. Table fields may be referenced unqualified (as defined in the table), args fields may be referenced by the "input" prefix.

args - Schema for tuples that will be an argument to this prepared query. May be null if not needed.

Returns:

A prepared query object which may be used to execute queries as long as this table is around.

Throws:

StreamBaseException - if the predicate fails to parse or there is some other issue with preparing the query

See Also:

• PreparedQuery

insert

void insert(Tuple row)
     throws StreamBaseException

Insert a new row into the table. Data will be copied into the table, the row object can be reused after the row is inserted.

Parameters:

row - Row values to insert into the able. Should not collide with existing row.

Throws:

StreamBaseException - If the table is read only or if the row collides with another row.

replace

Tuple replace(Tuple row)
       throws StreamBaseException

Replace a row in the table, or insert if there is no existing row with matching primary key. Data will be copied into the table, the row object can be reused after the row is inserted.

Parameters:

row - Row to replace with.

Returns:

The previous row, or null if there was no previous row. The row is read only.

Throws:

StreamBaseException - if the table is read only

delete

Tuple delete(Tuple pkey)
      throws StreamBaseException

Delete a row in the table based on primary key.

Parameters:

pkey - Row object to use for primary key data.

Returns:

Deleted row or null if there was no matching row. The row is read only.

Throws:

StreamBaseException - if the table is read only

truncate

void truncate()
       throws StreamBaseException

Truncate the table, by removing all rows

Throws:

StreamBaseException - Truncation failed

size

long size(boolean slowAndAccurate)

Return the number of rows in the table

Parameters:

slowAndAccurate - For some table implementations accurate results can be expensive. For in-memory query tables, exact results are inexpensive and always returned.

Returns:

The number of rows in the table

Since:

7.2.5