Version 2.0.1
ex_call_center.c

A more complex schema based on a call center example, showing how to map some SQL constructs onto the WiredTiger API.

/*-
* Public Domain 2008-2013 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_call_center.c
* This is an example application that demonstrates how to map a
* moderately complex SQL application into WiredTiger.
*/
#include <inttypes.h>
#include <stdio.h>
#include <string.h>
#include <wiredtiger.h>
const char *home = NULL;
/*
* In SQL, the tables are described as follows:
*
* CREATE TABLE Customers(id INTEGER PRIMARY KEY,
* name VARCHAR(30), address VARCHAR(50), phone VARCHAR(15))
* CREATE INDEX CustomersPhone ON Customers(phone)
*
* CREATE TABLE Calls(id INTEGER PRIMARY KEY, call_date DATE,
* cust_id INTEGER, emp_id INTEGER, call_type VARCHAR(12),
* notes VARCHAR(25))
* CREATE INDEX CallsCustDate ON Calls(cust_id, call_date)
*
* In this example, both tables will use record numbers for their IDs, which
* will be the key. The C structs for the records are as follows.
*/
/* Customer records. */
typedef struct {
uint64_t id;
const char *name;
const char *address;
const char *phone;
} CUSTOMER;
/* Call records. */
typedef struct {
uint64_t id;
uint64_t call_date;
uint64_t cust_id;
uint64_t emp_id;
const char *call_type;
const char *notes;
} CALL;
int main(void)
{
int count, exact, ret;
WT_CONNECTION *conn;
WT_SESSION *session;
WT_CURSOR *cursor;
CUSTOMER cust, *custp, cust_sample[] = {
{ 0, "Professor Oak", "LeafGreen Avenue", "123-456-7890" },
{ 0, "Lorelei", "Sevii Islands", "098-765-4321" },
{ 0, NULL, NULL, NULL }
};
CALL call, *callp, call_sample[] = {
{ 0, 32, 1, 2, "billing", "unavailable" },
{ 0, 33, 1, 2, "billing", "available" },
{ 0, 34, 1, 2, "reminder", "unavailable" },
{ 0, 35, 1, 2, "reminder", "available" },
{ 0, 0, 0, 0, NULL, NULL }
};
ret = wiredtiger_open(home, NULL, "create", &conn);
if (ret != 0) {
fprintf(stderr, "Error connecting to %s: %s\n",
home, wiredtiger_strerror(ret));
return (1);
}
/* Note: further error checking omitted for clarity. */
ret = conn->open_session(conn, NULL, NULL, &session);
/*
* Create the customers table, give names and types to the columns.
* The columns will be stored in two groups: "main" and "address",
* created below.
*/
ret = session->create(session, "table:customers",
"key_format=r,"
"value_format=SSS,"
"columns=(id,name,address,phone),"
"colgroups=(main,address)");
/* Create the main column group with value columns except address. */
ret = session->create(session,
"colgroup:customers:main", "columns=(name,phone)");
/* Create the address column group with just the address. */
ret = session->create(session,
"colgroup:customers:address", "columns=(address)");
/* Create an index on the customer table by phone number. */
ret = session->create(session,
"index:customers:phone", "columns=(phone)");
/* Populate the customers table with some data. */
ret = session->open_cursor(
session, "table:customers", NULL, "append", &cursor);
for (custp = cust_sample; custp->name != NULL; custp++) {
cursor->set_value(cursor,
custp->name, custp->address, custp->phone);
ret = cursor->insert(cursor);
}
ret = cursor->close(cursor);
/*
* Create the calls table, give names and types to the columns. All the
* columns will be stored together, so no column groups are declared.
*/
ret = session->create(session, "table:calls",
"key_format=r,"
"value_format=qrrSS,"
"columns=(id,call_date,cust_id,emp_id,call_type,notes)");
/*
* Create an index on the calls table with a composite key of cust_id
* and call_date.
*/
ret = session->create(session, "index:calls:cust_date",
"columns=(cust_id,call_date)");
/* Populate the calls table with some data. */
ret = session->open_cursor(
session, "table:calls", NULL, "append", &cursor);
for (callp = call_sample; callp->call_type != NULL; callp++) {
cursor->set_value(cursor, callp->call_date, callp->cust_id,
callp->emp_id, callp->call_type, callp->notes);
ret = cursor->insert(cursor);
}
ret = cursor->close(cursor);
/*
* First query: a call arrives. In SQL:
*
* SELECT id, name FROM Customers WHERE phone=?
*
* Use the cust_phone index, lookup by phone number to fill the
* customer record. The cursor will have a key format of "S" for a
* string because the cust_phone index has a single column ("phone"),
* which is of type "S".
*
* Specify the columns we want: the customer ID and the name. This
* means the cursor's value format will be "rS".
*/
ret = session->open_cursor(session,
"index:customers:phone(id,name)", NULL, NULL, &cursor);
cursor->set_key(cursor, "123-456-7890");
ret = cursor->search(cursor);
if (ret == 0) {
ret = cursor->get_value(cursor, &cust.id, &cust.name);
printf("Read customer record for %s (ID %" PRIu64 ")\n",
cust.name, cust.id);
}
ret = cursor->close(cursor);
/*
* Next query: get the recent order history. In SQL:
*
* SELECT * FROM Calls WHERE cust_id=? ORDER BY call_date DESC LIMIT 3
*
* Use the call_cust_date index to find the matching calls. Since it is
* is in increasing order by date for a given customer, we want to start
* with the last record for the customer and work backwards.
*
* Specify a subset of columns to be returned. (Note that if these were
* all covered by the index, the primary would not have to be accessed.)
* Stop after getting 3 records.
*/
ret = session->open_cursor(session,
"index:calls:cust_date(cust_id,call_type,notes)",
NULL, NULL, &cursor);
/*
* The keys in the index are (cust_id,call_date) -- we want the largest
* call date for a given cust_id. Search for (cust_id+1,0), then work
* backwards.
*/
cust.id = 1;
cursor->set_key(cursor, cust.id + 1, 0);
ret = cursor->search_near(cursor, &exact);
/*
* If the table is empty, search_near will return WT_NOTFOUND, else the
* cursor will be positioned on a matching key if one exists, or an
* adjacent key if one does not. If the positioned key is equal to or
* larger than the search key, go back one.
*/
if (ret == 0 && exact >= 0)
ret = cursor->prev(cursor);
for (count = 0; ret == 0 && count < 3; ++count) {
ret = cursor->get_value(cursor,
&call.cust_id, &call.call_type, &call.notes);
if (call.cust_id != cust.id)
break;
printf("Call record: customer %" PRIu64 " (%s: %s)\n",
call.cust_id, call.call_type, call.notes);
ret = cursor->prev(cursor);
}
ret = conn->close(conn, NULL);
return (ret);
}