Version 10.0.1
ex_backup.c

Shows how to use log-based incremental backup.

/*-
* 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_backup.c
* demonstrates how to use incremental backup and log files.
*/
#include <test_util.h>
static const char *const home = "WT_HOME_LOG";
static const char *const home_full = "WT_HOME_LOG_FULL";
static const char *const home_incr = "WT_HOME_LOG_INCR";
static const char *const full_out = "./backup_full";
static const char *const incr_out = "./backup_incr";
static const char *const uri = "table:logtest";
#define CONN_CONFIG "create,cache_size=100MB,log=(archive=false,enabled=true,file_max=100K)"
#define MAX_ITERATIONS 5
#define MAX_KEYS 10000
static int
compare_backups(int i)
{
int ret;
char buf[1024], msg[32];
/*
* We run 'wt dump' on both the full backup directory and the incremental backup directory for
* this iteration. Since running 'wt' runs recovery and makes both directories "live", we need a
* new directory for each iteration.
*
* If i == 0, we're comparing against the main, original directory with the final incremental
* directory.
*/
if (i == 0)
(void)snprintf(
buf, sizeof(buf), "../../wt -R -h %s dump logtest > %s.%d", home, full_out, i);
else
(void)snprintf(
buf, sizeof(buf), "../../wt -R -h %s.%d dump logtest > %s.%d", home_full, i, full_out, i);
error_check(system(buf));
/*
* Now run dump on the incremental directory.
*/
(void)snprintf(
buf, sizeof(buf), "../../wt -R -h %s.%d dump logtest > %s.%d", home_incr, i, incr_out, i);
error_check(system(buf));
/*
* Compare the files.
*/
(void)snprintf(buf, sizeof(buf), "cmp %s.%d %s.%d", full_out, i, incr_out, i);
ret = system(buf);
if (i == 0)
(void)snprintf(msg, sizeof(msg), "%s", "MAIN");
else
(void)snprintf(msg, sizeof(msg), "%d", i);
printf("Iteration %s: Tables %s.%d and %s.%d %s\n", msg, full_out, i, incr_out, i,
ret == 0 ? "identical" : "differ");
if (ret != 0)
exit(1);
/*
* If they compare successfully, clean up.
*/
if (i != 0) {
(void)snprintf(buf, sizeof(buf), "rm -rf %s.%d %s.%d %s.%d %s.%d", home_full, i, home_incr,
i, full_out, i, incr_out, i);
error_check(system(buf));
}
return (ret);
}
/*
* Set up all the directories needed for the test. We have a full backup directory for each
* iteration and an incremental backup for each iteration. That way we can compare the full and
* incremental each time through.
*/
static void
setup_directories(void)
{
int i;
char buf[1024];
for (i = 0; i < MAX_ITERATIONS; i++) {
/*
* For incremental backups we need 0-N. The 0 incremental directory will compare with the
* original at the end.
*/
(void)snprintf(buf, sizeof(buf), "rm -rf %s.%d && mkdir %s.%d", home_incr, i, home_incr, i);
error_check(system(buf));
if (i == 0)
continue;
/*
* For full backups we need 1-N.
*/
(void)snprintf(buf, sizeof(buf), "rm -rf %s.%d && mkdir %s.%d", home_full, i, home_full, i);
error_check(system(buf));
}
}
static void
add_work(WT_SESSION *session, int iter)
{
WT_CURSOR *cursor;
int i;
char k[32], v[32];
error_check(session->open_cursor(session, uri, NULL, NULL, &cursor));
/*
* Perform some operations with individual auto-commit transactions.
*/
for (i = 0; i < MAX_KEYS; i++) {
(void)snprintf(k, sizeof(k), "key.%d.%d", iter, i);
(void)snprintf(v, sizeof(v), "value.%d.%d", iter, i);
cursor->set_key(cursor, k);
cursor->set_value(cursor, v);
error_check(cursor->insert(cursor));
}
error_check(cursor->close(cursor));
}
static void
take_full_backup(WT_SESSION *session, int i)
{
WT_CURSOR *cursor;
int j, ret;
char buf[1024], h[256];
const char *filename, *hdir;
/*
* First time through we take a full backup into the incremental directories. Otherwise only
* into the appropriate full directory.
*/
if (i != 0) {
(void)snprintf(h, sizeof(h), "%s.%d", home_full, i);
hdir = h;
} else
hdir = home_incr;
error_check(session->open_cursor(session, "backup:", NULL, NULL, &cursor));
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(cursor, &filename));
if (i == 0)
/*
* Take a full backup into each incremental directory.
*/
for (j = 0; j < MAX_ITERATIONS; j++) {
(void)snprintf(h, sizeof(h), "%s.%d", home_incr, j);
(void)snprintf(buf, sizeof(buf), "cp %s/%s %s/%s", home, filename, h, filename);
error_check(system(buf));
}
else {
(void)snprintf(h, sizeof(h), "%s.%d", home_full, i);
(void)snprintf(buf, sizeof(buf), "cp %s/%s %s/%s", home, filename, hdir, filename);
error_check(system(buf));
}
}
scan_end_check(ret == WT_NOTFOUND);
error_check(cursor->close(cursor));
}
static void
take_incr_backup(WT_SESSION *session, int i)
{
WT_CURSOR *cursor;
int j, ret;
char buf[1024], h[256];
const char *filename;
error_check(session->open_cursor(session, "backup:", NULL, "target=(\"log:\")", &cursor));
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(cursor, &filename));
/*
* Copy into the 0 incremental directory and then each of the incremental directories for
* this iteration and later.
*/
(void)snprintf(h, sizeof(h), "%s.0", home_incr);
(void)snprintf(buf, sizeof(buf), "cp %s/%s %s/%s", home, filename, h, filename);
error_check(system(buf));
for (j = i; j < MAX_ITERATIONS; j++) {
(void)snprintf(h, sizeof(h), "%s.%d", home_incr, j);
(void)snprintf(buf, sizeof(buf), "cp %s/%s %s/%s", home, filename, h, filename);
error_check(system(buf));
}
}
scan_end_check(ret == WT_NOTFOUND);
/*
* With an incremental cursor, we want to truncate on the backup cursor to archive the logs.
* Only do this if the copy process was entirely successful.
*/
error_check(session->truncate(session, "log:", cursor, NULL, NULL));
error_check(cursor->close(cursor));
}
int
main(int argc, char *argv[])
{
WT_CONNECTION *wt_conn;
WT_SESSION *session;
int i;
char cmd_buf[256];
(void)argc; /* Unused variable */
(void)testutil_set_progname(argv);
(void)snprintf(cmd_buf, sizeof(cmd_buf), "rm -rf %s && mkdir %s", home, home);
error_check(system(cmd_buf));
error_check(wiredtiger_open(home, NULL, CONN_CONFIG, &wt_conn));
setup_directories();
error_check(wt_conn->open_session(wt_conn, NULL, NULL, &session));
error_check(session->create(session, uri, "key_format=S,value_format=S"));
printf("Adding initial data\n");
add_work(session, 0);
printf("Taking initial backup\n");
take_full_backup(session, 0);
error_check(session->checkpoint(session, NULL));
for (i = 1; i < MAX_ITERATIONS; i++) {
printf("Iteration %d: adding data\n", i);
add_work(session, i);
error_check(session->checkpoint(session, NULL));
/*
* The full backup here is only needed for testing and comparison purposes. A normal
* incremental backup procedure would not include this.
*/
printf("Iteration %d: taking full backup\n", i);
take_full_backup(session, i);
/*
* Taking the incremental backup also calls truncate to archive the log files, if the copies
* were successful. See that function for details on that call.
*/
printf("Iteration %d: taking incremental backup\n", i);
take_incr_backup(session, i);
printf("Iteration %d: dumping and comparing data\n", i);
error_check(compare_backups(i));
}
/*
* Close the connection. We're done and want to run the final comparison between the incremental
* and original.
*/
error_check(wt_conn->close(wt_conn, NULL));
printf("Final comparison: dumping and comparing data\n");
error_check(compare_backups(0));
return (EXIT_SUCCESS);
}
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_CURSOR::get_key
int get_key(WT_CURSOR *cursor,...)
Get the key for the current record.
WT_CURSOR
A WT_CURSOR handle is the interface to a cursor.
Definition: wiredtiger.in:211
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_CURSOR::next
int next(WT_CURSOR *cursor)
Return the next record.
WT_SESSION::truncate
int truncate(WT_SESSION *session, const char *name, WT_HANDLE_NULLABLE(WT_CURSOR) *start, WT_HANDLE_NULLABLE(WT_CURSOR) *stop, const char *config)
Truncate a file, table, cursor range, or backup cursor.
WT_CONNECTION
A connection to a WiredTiger database.
Definition: wiredtiger.in:1968
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_SESSION::checkpoint
int checkpoint(WT_SESSION *session, const char *config)
Write a transactionally consistent snapshot of a database or set of objects.
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_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_CURSOR::insert
int insert(WT_CURSOR *cursor)
Insert a record and optionally update an existing record.