QUERYBUFFERSTATS System Table Description

Description

A pseudo table generated to show queries that have used significant amounts of memory. This is currently limited to sorting operations (those running queries that use the ORDER BY clause). Support for additional operations will be added in future releases of NuoDB.

By default, the ten queries with the highest memory usage in compatible processing modules are stored in the QUERYBUFFERSTATS table. The number of queries listed is configurable using the MAX_QUERY_COUNT system property. For more information on using MAX_QUERY_COUNT, see SQL System Properties.

Fields

Field Type Description

SQLSTRING

string

The SQL statement requiring memory when executed.

USER

string

The SQL user for the database connection.

SCHEMA

string

The current SQL schema for the connection at the time of invocation of the query.

PARAMS

string

A string representing parameters specified in the query. The string representing each parameter is of the format:

n/type/value

Where:

n is the number of the parameter starting at 0.
type is the type of the variable, i.e. integer, string, etc.
value is the value passed to the parameter.

Each parameter string is separated by a space. For example:

NUMPARAM

PARAMS

\-------------------

\---------------------------

2

0/string/'hello' 1/integer/3

NODEID

bigint

A unique identifier specifying which TE the query’s client was connected to.

DATA_BUFFERING_MB

bigint

The peak amount of memory buffering required to process this query. For more information, refer to DISKSPILL_MEMORY_THRESHOLD in SQL System Properties.

TIMESTAMP

string

The timestamp for when the query began.

Indexes

Primary Index: VERSIONS..PRIMARY_KEY on field: PROPERTY