xSQL Configuration File Parameters

As described in xSQL Startup Options, a variety of configuration parameters control the behavior of xSQL. These parameters are specified in a configuration file that uses a JSON-like syntax with the following extensions:

1. Numeric literals may be hexadecimal (0x[0-9A-F]), octal (0[0-7]), or decimal.

2. Suffixes k/K (kilo), m/M (mega), and g/G (giga) are supported. or example, 100m means 100 x 1024 x 1024.

3. String values without whitespace or special characters do not require quotes.

4. Anything after a hash symbol (#) is treated as a comment (until the end of the line).

By default, xSQL looks for a file named xsql.cfg in the current working directory. This can be overridden using the -c command-line option.

If a parameter represents a bitwise combination of flags, it can be specified either as a single value or as an array:

a) "flags : value1" → flags = value1

b) "flags : [value1, value2, value3]" → flags = value1 | value2 | value3

c) "flags : []" → flags = 0

The following table lists the top-level sections of the configuration file and their corresponding C API structures. Click the links for detailed descriptions:

runtime_configuration : {...}

Runtime configuration — specifies which libraries are loaded at startup.

runtime_options : {...}

Global eXtremeDB runtime options (mapped to mco_runtime_setoption()).

devices : [ {...} ]

Array of device descriptors (mco_device_t) and shortcut parameters.

schema

Database schema definition (inline DDL).

db_params : {...}

Database parameters (mco_db_params_t).

SQL parameters

Settings that affect SQL engine behavior (e.g., port, trace, statement execution).

tl_params : {...}

Transaction Logging parameters (mco_TL_start_data_t).

ha_params : {...}

High Availability parameters (mco_HA_master_params_t and mco_HA_replica_params_t).

cluster_params : {...}

Cluster configuration (mco_cluster_params_t).

iot_params : {...}

Active replication parameters.

ssl_params : {...}

OpenSSL configuration (mco_ssl_params_t).

perfmon : {...}

Performance Monitor settings (enables runtime metric collection in xSQL).

rest : {...}

Embedded REST server configuration — exposes the Web Services REST API.

xlog_params : {...}

Statistics logging parameters.

trace_params : {...}

Tracing Framework settings.

Miscellaneous parameters

Additional settings affecting eXtremeDB runtime behavior.

Persistent Media I/O

Asynchronous I/O and multi-file storage format options.

Note: In general, configuration file sections map directly to C API structures used by functions such as: mco_db_open_dev(), mco_cluster_db_open(), mco_HA_attach_master(), and mco_HA_attach_replica(). For example:

• The devices section corresponds to the mco_device_t array passed to mco_db_open_dev().
• The db_params section maps to the mco_db_params_t structure.
• The cluster_params section reflects mco_cluster_params_t.

Note: Command-line options take precedence over configuration file settings. If a parameter is specified both in the file and on the command line, the command-line value will be used.