Running Niagara-2

This is a brief listing of tweaks you can do to a compiled Niagara query engine. These tweaks enable minimal diagnostic output so you can try to determine what is going on without needing to recompile.

For now, all these tweaks are controlled by environment variables. While not elegant, it works. Unless mentioned otherwise, most of these take numeric values. If the environment variable is not set, or is set to 0, or a negative integer value, or something that doesn't parse as an integer, the tweak will be turned off. If it is set to a non-negative integer, the tweak will be enabled.

Query Engine

NIAGARA_DUMP_AST

Dump the Abstract Syntax Tree generated by the parser.

NIAGARA_DUMP_PLAN_LOGICAL

Dump the logical plan that is generated by the query engine.

NIAGARA_DUMP_PLAN_PHYSICAL

Dump the physical plan that is generated by the query engine.

Runtime Environment for Shore

NIAGARA_SM_CONFIG

NIAGARA_CONFIG

Location of the shore options file used to configure a niagara shore database instance. The default is './config.niagara'.

NIAGARA_SM_FORMAT

Format the log and volumes listed in the config file, instead of using whatever is there. Currently this is the only way to format the store.

NIAGARA_STACKSIZE

Set the stacksize of threads created for Niagara. The range of this is Positive Integer Values. Recommended sizes are larger than 64k. The default stacksize of shore threads is 64k; and the default Niagara thread stacksize is currently 2MB.

Runtime Environment for libdb

NIAGARA_DB_DIR

Directory where the libdb database is created.

NIAGARA_DB_FORMAT

Format the libdb database instance used, instead of using whatever is there. Currently this it the only way to format the store explicitly. However, the libdb wrapper code will automagically format a db if it is missing.

NIAGARA_DB_BUFFERPOOL

Specify the size of the buffer pool that libdb uses. The default buffer pool size is 16MB, which corresponds to the individual 8MB + 8MB buffer pools used by the old individual IM and DM libdb instances.

NIAGARA_DB_LOCKMAX

Specify the maximum number of locks that the libdb instance should be created with. The default number of locks is 100,000.