LOCALCONNECTIONS System Table Description

Description

A pseudo table. SYSTEM.LOCALCONNECTIONS is similar to the pseudo table SYSTEM.CONNECTIONS, except it only lists connections to the same Transaction Engine (TE) to which the current client is connected. The SYSTEM.LOCALCONNECTIONS pseudo table does not include some columns that are defined for the SYSTEM.CONNECTIONS pseudo table.

Client applications should never contain code that accesses SYSTEM pseudo tables as they are subject to, and furthermore likely to, change from release to release.

Fields

Field Name Type Description

SQLSTRING

string

The SQL statement being executed. If the connection is currently active, but no statement is executing, the SQLSTRING is presented as an empty string.

COUNT

integer

A number n, indicating that this is the nth statement executed on this connection.

RUNTIME

bigint

The duration of the statement execution specified in microseconds.

USER

string

The SQL user for the database connection.

SCHEMA

string

The current SQL schema for the database connection.

NUMPARAM

integer

The number of SQL parameters specified in the query. This is 0 if no parameters were specified or if no statement is executing.

PARAMS

string

Parameter string — A string representing the 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, for example, integer, string.

value is the value passed in to the parameter.

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

NUMPARAM            PARAMS
--------- ----------------------------
    2     0/string/'hello' 1/integer/16

CONNID

bigint

A connection identifier which is unique across all connections in the database.

OPEN

integer

The number of open statements created using this connection.

MEMUSAGE

bigint

An estimate of the current memory usage by this connection.

HANDLE

integer

An identifier, unique only to the specific connection, that represents the executing statement. HANDLE is -1 when there is no statement running on the connection.

OPENRESULTS

integer

The number of open result sets for this connection.

TRANSID

bigint

The identifier for the transaction being run on the connection. This value can be used to query SYSTEM.TRANSACTIONS by ID.

TRANSRUNTIME

bigint

The duration of the current open transaction on the connection, specified in microseconds.

AUTOCOMMITFLAGS

integer

A bitwise mapping of the following values

0x1

Autocommit is on.

0x2

Autocommit is deferred, meaning defer commit on read operations until the result set is closed or the next operation occurs.

0x4

Autocommit is suspended.

ISOLATIONLEVEL

integer

Specifies the transaction isolation level for the connection:

2	`READ COMMITTED`
4	`REPEATABLE READ`
7	`CONSISTENT READ`
8	`SERIALIZABLE`

CLIENTHOST

string

Specifies the IP address for the connecting client. The TE will supply this with information from the socket it uses for communicating with the client.

CLIENTPROCESSID

string

Specifies the process ID (pid) for the connecting client. This may be set automatically by the C++, .NET, and Python drivers. Otherwise, this must be given as the client connection property clientProcessID. See Connection Properties for more information.

CLIENTINFO

string

Specifies the client information for the connecting client. This must be given as the client connection property clientInfo. See Connection Properties for more information.

ROLLBACKMODE

string

Either TRANSACTION, PROCEDURE, or OFF. See SET ROLLBACK MODE at SET

EXECUTIONSTACK

string

The execution stack column details all nested calls in the procedure currently running. The current executing statement, at the top of the stack, is shown at the top of this column.

CREATED

timestamp

The date and time when this connection was established with NUODB.

LASTEXECUTED

timestamp

The date and time when this connection last executed SQL.

SQLENGINE

string

The SQL Engine and the optimizer used by the connection.

Indexes

None

Example

The following example shows three rows in SYSTEM.LOCALCONNECTIONS. The first row represents a SQL statement executing on another client with two parameters in the query. We use SET OUTPUT VERTICAL because there are many columns in SYSTEM.LOCALCONNECTIONS and it is more readable if displayed this way. The second row represents an example of how a SQL multi-statement might appear in the table with the executionstack providing information about what is being executed. The third row represents the SELECT * FROM system.localconnections query itself.

In the row for the first query, we see this is the first statement run on this connection. The query has been running 2016795 microseconds (or 2.0 seconds), the SQL user is DBA and the current schema is USER, and the parameters entered for the query were A% and 16. The AUTOCOMMITFLAGS is set to 7 which means autocommit is on but deferred on read operations until the result set is closed or the next operation occurs. The transaction isolation level is SERIALIZABLE.

SET OUTPUT VERTICAL;

SELECT * FROM system.localconnections;
==================================== Row #1 ====================================
SQLSTRING: select * from hugetable where lastname like ? and id > ?;
COUNT: 1
RUNTIME: 2016795
USER: DBA
SCHEMA: USER
NUMPARAM: 2
PARAMS: 0/string/A% 1/string/16
CONNID: 21474836521
OPEN: 2
MEMUSAGE: 15552
HANDLE: 9
OPENRESULTS: 1
TRANSID: 4548485
TRANSRUNTIME: 2016689
AUTOCOMMITFLAGS: 7
ISOLATIONLEVEL: 8
CLIENTHOST: 127.0.0.1
CLIENTPROCESSID: 38483
CLIENTINFO: nuosql
ROLLBACKMODE: procedure
EXECUTIONSTACK:
CREATED: 2018-04-19 10:26:15.616959
LASTEXECUTED: 2018-04-19 10:39:53.891211
SQLENGINE: Vectorized with v3 optimizer
==================================== Row #2 ====================================
SQLSTRING: var x = 0; while (x < 10) execute immediate 'insert into employees.titles values (?), (?), (?);' using values 1, 2, x; x = x + 1; end_while;
COUNT: 2
RUNTIME: 9214554
USER: DBA
SCHEMA: USER
NUMPARAM: 0
PARAMS:
CONNID: 21474836522
OPEN: 2
MEMUSAGE: 15552
HANDLE: 1
OPENRESULTS: 1
TRANSID: 4548357
TRANSRUNTIME: 9214479
AUTOCOMMITFLAGS: 5
ISOLATIONLEVEL: 8
CLIENTHOST: 127.0.0.1
CLIENTPROCESSID: 38872
CLIENTINFO: nuosql
ROLLBACKMODE: procedure
EXECUTIONSTACK: Procedure "SAMPLE.PROC" line 1: insert into sample.b select msleep(1000) from dual
Procedure "EMPLOYEES.PROC2" line 1: call sample.proc()
Trigger "EMPLOYEES.TITLES.TRIG1" line 1: call proc2(NEW.f1)
line 1: execute immediate 'insert into employees.titles values (?), (?), (?);' using values 1, 2, x
CREATED: 2018-04-19 10:38:18.631389
LASTEXECUTED: 2018-04-19 10:39:46.691568
SQLENGINE: Vectorized with v3 optimizer
==================================== Row #3 ====================================
SQLSTRING: SELECT * FROM system.localconnections;
COUNT: 4
RUNTIME: 159
USER: DBA
SCHEMA: USER
NUMPARAM: 0
PARAMS:
CONNID: 21474836523
OPEN: 1
MEMUSAGE: 15552
HANDLE: 1
OPENRESULTS: 0
TRANSID: 4548613
TRANSRUNTIME: 81
AUTOCOMMITFLAGS: 1
ISOLATIONLEVEL: 8
CLIENTHOST: 127.0.0.1
CLIENTPROCESSID: 38873
CLIENTINFO: nuosql
ROLLBACKMODE: procedure
EXECUTIONSTACK:
CREATED: 2018-04-19 10:38:23.287194
LASTEXECUTED: 2018-04-19 10:39:55.906553
SQLENGINE: Vectorized with v3 optimizer