Version 10.0.1
ex_cursor.c

Shows some common cursor types and operations.

/*-
* 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_cursor.c
* This is an example demonstrating some cursor types and operations.
*/
#include <test_util.h>
int cursor_reset(WT_CURSOR *cursor);
int cursor_forward_scan(WT_CURSOR *cursor);
int cursor_reverse_scan(WT_CURSOR *cursor);
int cursor_search(WT_CURSOR *cursor);
int cursor_search_near(WT_CURSOR *cursor);
int cursor_insert(WT_CURSOR *cursor);
int cursor_update(WT_CURSOR *cursor);
int cursor_remove(WT_CURSOR *cursor);
int cursor_largest_key(WT_CURSOR *cursor);
static const char *home;
int
cursor_forward_scan(WT_CURSOR *cursor)
{
const char *key, *value;
int ret;
while ((ret = cursor->next(cursor)) == 0) {
error_check(cursor->get_key(cursor, &key));
error_check(cursor->get_value(cursor, &value));
}
scan_end_check(ret == WT_NOTFOUND);
return (0);
}
int
cursor_reverse_scan(WT_CURSOR *cursor)
{
const char *key, *value;
int ret;
while ((ret = cursor->prev(cursor)) == 0) {
error_check(cursor->get_key(cursor, &key));
error_check(cursor->get_value(cursor, &value));
}
scan_end_check(ret == WT_NOTFOUND);
return (0);
}
int
cursor_reset(WT_CURSOR *cursor)
{
return (cursor->reset(cursor));
}
int
cursor_search(WT_CURSOR *cursor)
{
const char *value;
cursor->set_key(cursor, "foo");
error_check(cursor->search(cursor));
error_check(cursor->get_value(cursor, &value));
return (0);
}
int
cursor_search_near(WT_CURSOR *cursor)
{
const char *key, *value;
int exact;
cursor->set_key(cursor, "foo");
error_check(cursor->search_near(cursor, &exact));
switch (exact) {
case -1: /* Returned key smaller than search key */
error_check(cursor->get_key(cursor, &key));
break;
case 0: /* Exact match found */
break;
case 1: /* Returned key larger than search key */
error_check(cursor->get_key(cursor, &key));
break;
}
error_check(cursor->get_value(cursor, &value));
return (0);
}
int
cursor_insert(WT_CURSOR *cursor)
{
cursor->set_key(cursor, "foo");
cursor->set_value(cursor, "bar");
return (cursor->insert(cursor));
}
int
cursor_update(WT_CURSOR *cursor)
{
cursor->set_key(cursor, "foo");
cursor->set_value(cursor, "newbar");
return (cursor->update(cursor));
}
int
cursor_remove(WT_CURSOR *cursor)
{
cursor->set_key(cursor, "foo");
return (cursor->remove(cursor));
}
int
cursor_largest_key(WT_CURSOR *cursor)
{
return (cursor->largest_key(cursor));
}
int
main(int argc, char *argv[])
{
WT_CURSOR *cursor;
WT_SESSION *session;
home = example_setup(argc, argv);
/* Open a connection to the database, creating it if necessary. */
error_check(wiredtiger_open(home, NULL, "create,statistics=(fast)", &conn));
/* Open a session for the current thread's work. */
error_check(conn->open_session(conn, NULL, NULL, &session));
error_check(session->create(session, "table:world",
"key_format=r,value_format=5sii,columns=(id,country,population,area)"));
error_check(session->open_cursor(session, "table:world", NULL, NULL, &cursor));
error_check(
session->open_cursor(session, "table:world(country,population)", NULL, NULL, &cursor));
error_check(session->open_cursor(session, "statistics:", NULL, NULL, &cursor));
/* Create a simple string table to illustrate basic operations. */
error_check(session->create(session, "table:map", "key_format=S,value_format=S"));
error_check(session->open_cursor(session, "table:map", NULL, NULL, &cursor));
error_check(cursor_insert(cursor));
error_check(cursor_reset(cursor));
error_check(cursor_forward_scan(cursor));
error_check(cursor_reset(cursor));
error_check(cursor_reverse_scan(cursor));
error_check(cursor_search_near(cursor));
error_check(cursor_update(cursor));
error_check(cursor_remove(cursor));
error_check(cursor_largest_key(cursor));
error_check(cursor->close(cursor));
/* Note: closing the connection implicitly closes open session(s). */
error_check(conn->close(conn, NULL));
return (EXIT_SUCCESS);
}
WT_CURSOR::prev
int prev(WT_CURSOR *cursor)
Return the previous record.
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_CURSOR::search
int search(WT_CURSOR *cursor)
Return the record matching the key.
WT_CURSOR::largest_key
int largest_key(WT_CURSOR *cursor)
Get the largest key of the cursor regardless of visibility.
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_CURSOR::reset
int reset(WT_CURSOR *cursor)
Reset the cursor.
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_CURSOR::search_near
int search_near(WT_CURSOR *cursor, int *exactp)
Return the record matching the key if it exists, or an adjacent record.
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_CURSOR::remove
int remove(WT_CURSOR *cursor)
Remove a record.
WT_CURSOR::update
int update(WT_CURSOR *cursor)
Update an existing record and optionally insert a record.
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.