Welcome to SAIO’s documentation!¶

saio¶

default: true

A boolean that enables or disables using SAIO for planning. If true, all queries with number of joins exceeding saio_threshold will be planned with SAIO, if false none.

saio_threshold¶

range: 0 to INT_MAX
default: 14

Determines the threshold of FROM items beyond which SAIO is used.

For smaller queries it is suitable to optimize join order with PostgreSQL default exhaustive optimizer.

saio_seed¶

range: 0.0 to 1.0
default: 0.0

A floating point seed for the random numbers generator. If saio_seed is set to 0.0, the algorithm will randomize the seed with time(NULL). For other values, it will use the fixed seed provided.

saio_equilibrium_factor¶

range: 1 to INT_MAX
default: 16

Scaling factor for the query size, determining the number of loops before equilibrium is reached.

Higher equilibrium_factor gives SAIO possibility to visit more states but increases the computation time.

saio_initial_temperature_factor¶

range: 0.0 to 10.0
default: 2.0

Factor determining the initial temperature of the system.

Higher saio_initial_temperature_factor gives SAIO possibility to visit more states but increases the computation time.

saio_temperature_reduction_factor¶

range: 0.0 to 1.0
default: 0.9

Factor determining how much the temperature is reduced each time equilibrium is reached.

Lower saio_temperature_reduction_factor gives SAIO possibility to visit more states but greatly increases the computation time.

saio_moves_before_frozen¶

range: 1 to INT_MAX
default: 4

How many moves without a state change are considered a freezing condition.

doc¶

Contains this documentation. To build it use:

make html

in the doc directory

scripts¶

Contains various snippets useful for the purpose of debugging SAIO.

src¶

Contains SAIO headers and source files. The code is well documented so there is no point in repeating the comments here.

do {
    do {
        new_state = random_move()
        if (acceptable(new_state))
            state = new_state
    }
    while (!equilibrium())
    reduce_temperature()
}
while (!frozen())
return state

SaioAlgorithm algorithm = {
    .step = saio_recalc_step,
    .initialize = saio_recalc_initialize,
    .finalize = saio_recalc_finalize
};

test¶

Contains regression tests for SAIO. To run tests go to the top directory and use:

make installcheck

The tests will be run in alphabetical order.

For a test to pass the output generated from running an sql script from the sql subdirectory must be identical to the corresponding .out file from the expected subdirectory.

It is also possible to generate test coverage reports through gcov and lcov. To use this you need to have your PostgreSQL installed from the source code with --with-coverage flag enabled.

./configure --with-coverage

To generate coverage reports for SAIO run:

make installcheck
make coverage

This will generate coverage directory with the coverage report. The test coverage should be ideally kept in the range of 95%-100%.