mongo/examples/python/ex_stat.py

#!/usr/bin/env python
#
# Public Domain 2014-2016 MongoDB, Inc.
# Public Domain 2008-2014 WiredTiger, Inc.
#
# This is free and unencumbered software released into the public domain.
#
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# distribute this software, either in source code form or as a compiled
# binary, for any purpose, commercial or non-commercial, and by any
# means.
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# of this software dedicate any and all copyright interest in the
# software to the public domain. We make this dedication for the benefit
# of the public at large and to the detriment of our heirs and
# successors. We intend this dedication to be an overt act of
# relinquishment in perpetuity of all present and future rights to this
# software under copyright law.
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# ex_stat.py
#      This is an example demonstrating how to query database statistics.

import os
from wiredtiger import wiredtiger_open,WIREDTIGER_VERSION_STRING,stat


def main():
    # Create a clean test directory for this run of the test program
    os.system('rm -rf WT_HOME')
    os.makedirs('WT_HOME')
    # Connect to the database and open a session
    conn = wiredtiger_open('WT_HOME', 'create,statistics=(all)')
    session = conn.open_session()

    # Create a simple table
    session.create('table:access', 'key_format=S,value_format=S')

    # Open a cursor and insert a record
    cursor = session.open_cursor('table:access', None)

    cursor['key'] = 'value'
    cursor.close()

    session.checkpoint()
    print WIREDTIGER_VERSION_STRING
    print_database_stats(session)
    print_file_stats(session)
    print_overflow_pages(session)
    print_derived_stats(session)
    conn.close()


def print_database_stats(session):
    statcursor = session.open_cursor("statistics:")
    print_cursor(statcursor)
    statcursor.close()


def print_file_stats(session):
    fstatcursor = session.open_cursor("statistics:table:access")
    print_cursor(fstatcursor)
    fstatcursor.close()


def print_overflow_pages(session):
    ostatcursor = session.open_cursor("statistics:table:access")
    val = ostatcursor[stat.dsrc.btree_overflow]
    if val != 0:
        print '%s=%s' % (str(val[0]), str(val[1]))
    ostatcursor.close()


def print_derived_stats(session):
    dstatcursor = session.open_cursor("statistics:table:access")
    ckpt_size = dstatcursor[stat.dsrc.block_checkpoint_size][1]
    file_size = dstatcursor[stat.dsrc.block_size][1]
    percent = 0
    if file_size != 0:
        percent = 100 * ((float(file_size) - float(ckpt_size)) / float(file_size))
    print "Table is %%%s fragmented" % str(percent)

    app_insert = int(dstatcursor[stat.dsrc.cursor_insert_bytes][1])
    app_remove = int(dstatcursor[stat.dsrc.cursor_remove_bytes][1])
    app_update = int(dstatcursor[stat.dsrc.cursor_update_bytes][1])
    fs_writes = int(dstatcursor[stat.dsrc.cache_bytes_write][1])

    if app_insert + app_remove + app_update != 0:
        print "Write amplification is " + '{:.2f}'.format(fs_writes / (app_insert + app_remove + app_update))
    dstatcursor.close()


def print_cursor(mycursor):
    while mycursor.next() == 0:
        val = mycursor.get_value()
        if val[1] != '0':
            print '%s=%s' % (str(val[0]), str(val[1]))

if __name__ == "__main__":
    main()