Version 10.0.1
ex_stat.c

Shows how to access database and table statistics.

/*-
* Public Domain 2014-present MongoDB, Inc.
* Public Domain 2008-2014 WiredTiger, Inc.
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* 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.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ex_stat.c
* This is an example demonstrating how to query database statistics.
*/
#include <test_util.h>
void get_stat(WT_CURSOR *cursor, int stat_field, int64_t *valuep);
void print_cursor(WT_CURSOR *);
void print_database_stats(WT_SESSION *);
void print_derived_stats(WT_SESSION *);
void print_file_stats(WT_SESSION *);
void print_join_cursor_stats(WT_SESSION *);
void print_overflow_pages(WT_SESSION *);
void print_session_stats(WT_SESSION *);
static const char *home;
void
print_cursor(WT_CURSOR *cursor)
{
const char *desc, *pvalue;
int64_t value;
int ret;
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_value(cursor, &desc, &pvalue, &value));
if (value != 0)
printf("%s=%s\n", desc, pvalue);
}
scan_end_check(ret == WT_NOTFOUND);
}
void
print_database_stats(WT_SESSION *session)
{
WT_CURSOR *cursor;
error_check(session->open_cursor(session, "statistics:", NULL, NULL, &cursor));
print_cursor(cursor);
error_check(cursor->close(cursor));
}
void
print_file_stats(WT_SESSION *session)
{
WT_CURSOR *cursor;
error_check(session->open_cursor(session, "statistics:table:access", NULL, NULL, &cursor));
print_cursor(cursor);
error_check(cursor->close(cursor));
}
void
print_join_cursor_stats(WT_SESSION *session)
{
WT_CURSOR *idx_cursor, *join_cursor, *stat_cursor;
error_check(session->create(session, "index:access:idx", "columns=(v)"));
error_check(session->open_cursor(session, "index:access:idx", NULL, NULL, &idx_cursor));
error_check(idx_cursor->next(idx_cursor));
error_check(session->open_cursor(session, "join:table:access", NULL, NULL, &join_cursor));
error_check(session->join(session, join_cursor, idx_cursor, "compare=gt"));
print_cursor(join_cursor);
error_check(session->open_cursor(session, "statistics:join", join_cursor, NULL, &stat_cursor));
print_cursor(stat_cursor);
error_check(stat_cursor->close(stat_cursor));
error_check(join_cursor->close(join_cursor));
error_check(idx_cursor->close(idx_cursor));
}
void
print_session_stats(WT_SESSION *session)
{
WT_CURSOR *stat_cursor;
error_check(session->open_cursor(session, "statistics:session", NULL, NULL, &stat_cursor));
print_cursor(stat_cursor);
error_check(stat_cursor->close(stat_cursor));
}
void
print_overflow_pages(WT_SESSION *session)
{
WT_CURSOR *cursor;
const char *desc, *pvalue;
int64_t value;
error_check(session->open_cursor(session, "statistics:table:access", NULL, NULL, &cursor));
error_check(cursor->search(cursor));
error_check(cursor->get_value(cursor, &desc, &pvalue, &value));
printf("%s=%s\n", desc, pvalue);
error_check(cursor->close(cursor));
}
void
get_stat(WT_CURSOR *cursor, int stat_field, int64_t *valuep)
{
const char *desc, *pvalue;
cursor->set_key(cursor, stat_field);
error_check(cursor->search(cursor));
error_check(cursor->get_value(cursor, &desc, &pvalue, valuep));
}
void
print_derived_stats(WT_SESSION *session)
{
WT_CURSOR *cursor;
error_check(session->open_cursor(session, "statistics:table:access", NULL, NULL, &cursor));
{
int64_t ckpt_size, file_size, percent;
get_stat(cursor, WT_STAT_DSRC_BLOCK_CHECKPOINT_SIZE, &ckpt_size);
get_stat(cursor, WT_STAT_DSRC_BLOCK_SIZE, &file_size);
percent = 0;
if (file_size != 0)
percent = 100 * ((file_size - ckpt_size) / file_size);
printf("Table is %" PRId64 "%% fragmented\n", percent);
}
{
int64_t app_insert, app_remove, app_update, fs_writes;
get_stat(cursor, WT_STAT_DSRC_CURSOR_INSERT_BYTES, &app_insert);
get_stat(cursor, WT_STAT_DSRC_CURSOR_REMOVE_BYTES, &app_remove);
get_stat(cursor, WT_STAT_DSRC_CURSOR_UPDATE_BYTES, &app_update);
get_stat(cursor, WT_STAT_DSRC_CACHE_BYTES_WRITE, &fs_writes);
if (app_insert + app_remove + app_update != 0)
printf("Write amplification is %.2lf\n",
(double)fs_writes / (app_insert + app_remove + app_update));
}
error_check(cursor->close(cursor));
}
int
main(int argc, char *argv[])
{
WT_CURSOR *cursor;
WT_SESSION *session;
home = example_setup(argc, argv);
error_check(wiredtiger_open(home, NULL, "create,statistics=(all)", &conn));
error_check(conn->open_session(conn, NULL, NULL, &session));
error_check(
session->create(session, "table:access", "key_format=S,value_format=S,columns=(k,v)"));
error_check(session->open_cursor(session, "table:access", NULL, NULL, &cursor));
cursor->set_key(cursor, "key");
cursor->set_value(cursor, "value");
error_check(cursor->insert(cursor));
error_check(cursor->close(cursor));
error_check(session->checkpoint(session, NULL));
print_database_stats(session);
print_file_stats(session);
print_join_cursor_stats(session);
print_session_stats(session);
print_overflow_pages(session);
print_derived_stats(session);
error_check(conn->close(conn, NULL));
return (EXIT_SUCCESS);
}
WT_STAT_DSRC_CURSOR_REMOVE_BYTES
#define WT_STAT_DSRC_CURSOR_REMOVE_BYTES
cursor: remove key bytes removed
Definition: wiredtiger.in:6876
WT_SESSION::create
int create(WT_SESSION *session, const char *name, const char *config)
Create a table, column group, index or file.
WT_SESSION::open_cursor
int open_cursor(WT_SESSION *session, const char *uri, WT_HANDLE_NULLABLE(WT_CURSOR) *to_dup, const char *config, WT_CURSOR **cursorp)
Open a new cursor on a data source or duplicate an existing cursor.
WT_STAT_DSRC_BLOCK_CHECKPOINT_SIZE
#define WT_STAT_DSRC_BLOCK_CHECKPOINT_SIZE
block-manager: checkpoint size
Definition: wiredtiger.in:6406
WT_CURSOR
A WT_CURSOR handle is the interface to a cursor.
Definition: wiredtiger.in:211
WT_CURSOR::search
int search(WT_CURSOR *cursor)
Return the record matching the key.
WT_CONNECTION::open_session
int open_session(WT_CONNECTION *connection, WT_EVENT_HANDLER *event_handler, const char *config, WT_SESSION **sessionp)
Open a session.
WT_CURSOR::close
int close(WT_HANDLE_CLOSED(WT_CURSOR) *cursor)
Close the cursor.
WT_SESSION::join
int join(WT_SESSION *session, WT_CURSOR *join_cursor, WT_CURSOR *ref_cursor, const char *config)
Join a join cursor with a reference cursor.
WT_CURSOR::next
int next(WT_CURSOR *cursor)
Return the next record.
WT_CURSOR::get_value
int get_value(WT_CURSOR *cursor,...)
Get the value for the current record.
WT_CONNECTION
A connection to a WiredTiger database.
Definition: wiredtiger.in:1968
WT_STAT_DSRC_CURSOR_INSERT_BYTES
#define WT_STAT_DSRC_CURSOR_INSERT_BYTES
cursor: insert key and value bytes
Definition: wiredtiger.in:6858
WT_CONNECTION::close
int close(WT_HANDLE_CLOSED(WT_CONNECTION) *connection, const char *config)
Close a connection.
WT_CURSOR::set_value
void set_value(WT_CURSOR *cursor,...)
Set the value for the next operation.
WT_STAT_DSRC_CURSOR_UPDATE_BYTES
#define WT_STAT_DSRC_CURSOR_UPDATE_BYTES
cursor: update key and value bytes
Definition: wiredtiger.in:6892
WT_SESSION::checkpoint
int checkpoint(WT_SESSION *session, const char *config)
Write a transactionally consistent snapshot of a database or set of objects.
WT_STAT_DSRC_BTREE_OVERFLOW
#define WT_STAT_DSRC_BTREE_OVERFLOW
btree: overflow pages, only reported if tree_walk or all statistics are enabled
Definition: wiredtiger.in:6482
wiredtiger_open
int wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler, const char *config, WT_CONNECTION **connectionp)
Open a connection to a database.
WT_STAT_DSRC_CACHE_BYTES_WRITE
#define WT_STAT_DSRC_CACHE_BYTES_WRITE
cache: bytes written from cache
Definition: wiredtiger.in:6505
WT_CURSOR::set_key
void set_key(WT_CURSOR *cursor,...)
Set the key for the next operation.
WT_NOTFOUND
#define WT_NOTFOUND
Item not found.
Definition: wiredtiger.in:3758
WT_SESSION
All data operations are performed in the context of a WT_SESSION.
Definition: wiredtiger.in:753
WT_STAT_DSRC_BLOCK_SIZE
#define WT_STAT_DSRC_BLOCK_SIZE
block-manager: file size in bytes
Definition: wiredtiger.in:6416
WT_CURSOR::insert
int insert(WT_CURSOR *cursor)
Insert a record and optionally update an existing record.