Database

Warning

This page contains features that are unfinished, were never implemented, or have since been deprecated. We preserve these pages for archival purposes, and also as a foundational resource for prospective developers who may wish to implement the same or similar feature. Many of these pages provide robust explanations of the theory behind a particular module or feature that we hope readers will find useful.

This page does not reflect the current state of GridLAB-D™

MySQL database connection

Synopsis

object database {
  hostname "localhost";
  username "gridlabd";
  password "";
  schema "gridlabd";
  port 3306;
  socketname "/tmp/mysql.sock";
  clientflags COMPRESS|FOUND_ROWS|IGNORE_SIGPIPE|INTERACTIVE|LOCAL_FILES|MULTI_RESULTS|MULTI_STATEMENTS|NO_SCHEMA|ODBC|SSL|REMEMBER_OPTIONS;
  options SHOWQUERY|NOCREATE|NEWDB|OVERWRITE;
  on_init _file-name_ ;
  on_sync _file-name_ ;
  on_term _file-name_ ;
  sync_interval seconds ;
  tz_offset seconds ; 
  uses_dst FALSE; 
}

Description

At least one database object must defined for recorder, player, and collector objects to function using a database. Typically, if no connection is specified by these objects, the last database defined will be used automatically.

hostname

Specifies the MySQL server hostname. By default this is the default hostname, which is by default **127.0.0.1** or **localhost**.

username

Specifies the MySQL username. By default this is the default username, which is by default **gridlabd**.

password

Specifies the MySQL password. By default this is the default password, which is by default an empty string (i.e., none provided).

schema

Specifies the database schema to use. If none is specified, the default schema is used (which is by default _gridlabd_). If a blank schema name is specified, the modelname is used. The schema will be automatically created if it does not exist unless the NOCREATE option is specified.

port

Specifies the port used to access the MySQL server.

socketname

Specifies the socketname used to access the MySQL server (linux/Mac only)

clientflags

Sets client flags used when connecting to the server.

COMPRESS

Enables data compression in the client/server protocol.

FOUND_ROWS

Returns the number of rows found instead of the number of rows changed.

IGNORE_SIGPIPE

Prevents the client library from installing a SIGPIPE signal handler. This can be used to avoid conflicts with a handler that the application has already installed.

INTERACTIVE

Permit interactive_timeout seconds of inactivity (rather than wait_timeout seconds) before closing the connection. The client's session wait_timeout variable is set to the value of the session interactive_timeout variable.

LOCAL_FILES

Enable `LOAD DATA LOCAL` handling.

MULTI_RESULTS

Tell the server that the client can handle multiple result sets from multiple-statement executions or stored procedures. This flag is automatically enabled if MULTI_STATEMENTS is enabled. MULTI_RESULTS can be enabled when you call mysql_real_connect(), either explicitly by passing the MULTI_RESULTS flag itself, or implicitly by passing MULTI_STATEMENTS (which also enables MULTI_RESULTS). In MySQL 5.7, MULTI_RESULTS is enabled by default.

MULTI_STATEMENTS

Tell the server that the client may send multiple statements in a single string (separated by ; characters). If this flag is not set, multiple-statement execution is disabled. If you enable MULTI_STATEMENTS or MULTI_RESULTS, process the result for every call to `mysql_query()` or `mysql_real_query()` by using a loop that calls `mysql_next_result()` to determine whether there are more results. For an example, see [Section 25.8.17, "C API Support for Multiple Statement Execution"](http://dev.mysql.com/doc/refman/5.7/en/c-api-multiple-queries.html).

NO_SCHEMA

Do not permit db_name.tbl_name.col_name syntax. This is for ODBC. It causes the parser to generate an error if you use that syntax, which is useful for trapping bugs in some ODBC programs.

ODBC

Unused.

SSL

Use SSL (encrypted protocol). Do not set this option within an application program; it is set internally in the client library. Instead, use `mysql_ssl_set()` before calling `mysql_real_connect()`.

REMEMBER_OPTIONS

Remember options specified by calls to mysql_options(). Without this option, if mysql_real_connect() fails, you must repeat the mysql_options() calls before trying to connect again. With this option, the mysql_options() calls need not be repeated.

options

Set the table handling options.

SHOWQUERY

When the SHOWQUERY is specified, each query executed by the client is displayed as a verbose message.

NOCREATE

Disable automatic creation of tables that don't exist.

NEWDB

When the NEWDB option is specified, then the schema is destroyed before it used. CAUTION: this may cause loss of data and should be used with care, especially if the default schema _gridlabd_ is used.

OVERWRITE

Enable deletion of existing data when an object initializes for output to a table. CAUTION: this may cause loss of data.

on_init

Specifies the MySQL script to execute when the database object is initialized. Scripts support all valid MySQL commands, as well as the DUMP and BACKUP commands.

on_sync

Specifies the MySQL script to execute when the database object is synchronized. Scripts support all valid MySQL commands, as well as the DUMP and BACKUP commands.

on_term

Specifies the MySQL script to execute when the database object is termination. Scripts support all valid MySQL commands, as well as the DUMP and BACKUP commands.

sync_interval

Specifies the interval between database object synchronization events.

tz_offset

Specifies the number of seconds offset between database times and object timestamps.

uses_dst

Specifies whether tz_offset should consider summer time or daylight savings time rules.

Version

The database object was introduced in Hassayampa (Version 3.0).

  • mysql module
    • database class
    • recorder class
    • player class
    • collector class
    • MySQL Import/Export
  • Technical manuals
    • Programmer's manual
    • MySQL How To Guide