Objectified Interface

• Basic types
• DB - database pointer
• DBT - database `thang'
• Basic functions
• int db_create(DB **dbp, DBENV *dbenv, u_int32_t flags)
• returns 0 if successful, otherwise an error code
• for basic usage, dbenv is NULL
• for basic usage, flags can be 0
• int DB->open(DB *db, const char *file, const char *database, DBTYPE type, u_int32_t flags, int mode)
• returns 0 if successful, otherwise an error code
• file is the file name of the Berkeley database
• database is the optional name of a database in file, set to NULL for basic usage
• DBTYPE is one of DB_BTREE, DB_HASH, DB_QUEUE, DB_RECNO, DB_UNKNOWN
• flags should be set to DB_CREATE for basic usage
• mode is the permissions the file
• int DB->put(DB *db, DB_TXN *txnid, DBT *key, DBT *data, u_int32_t flags)
• returns 0 if successful, otherwise an error code
• txnid is a transaction id, set to NULL for basic usage
• key is a key to insert into the database
• data the value to be inserted with the key
• for basic usage, flags can be 0
• int DB->get(DB *db, DB_TXN *txnid, DBT *key, DBT *data, u_int32_t flags)
• returns 0 if successful, otherwise an error code
• txnid is a transaction id, set to NULL for basic usage
• key is the key to search for
• if the key is found in the database, the respective data value is stored in data
• for basic usage, flags can be set to 0
• DB->del(DB *db, DB_TXN *txnid, DBT *key, u_int32_t flags)
• returns 0 if successful, otherwise an error code
• txnid is a transaction id, set to NULL for basic usage
• key is the key to be deleted
• flags is currently unused and should be set to 0
• DB->close(DB *db, u_int32_t flags)
• returns 0 if successful, otherwise an error code
• for basic usage, flags can be set to 0

01   #include <stdio.h>
02   #include <db.h>
03   #include <unistd.h>
04   #include <string.h>
05
06   int main(int argc, char **argv)
07   {
08      DB *dbp;
09      DBT key,data;
10      int ret;
11
12      if(argc != 3) {
13              fprintf(stderr,"Usage: %s key data\n",argv[0]);
14              exit(1);
15      }
16
17      if((ret = db_create(&dbp,NULL,0)) != 0) {
18              fprintf(stderr,"create_db: %s\n",db_strerror(ret));
19      }
20      if((ret = dbp->open(dbp,"test.db",NULL,DB_BTREE,DB_CREATE,0644)) != 0) {
21              dbp->err(dbp,ret,"dbp->open()");
22              exit(1);
23      }
24
25      memset(&key,0,sizeof(key));
26      memset(&data,0,sizeof(data));
27      key.data = strdup(argv[1]);
28      key.size = strlen(argv[1]);
29      data.data = strdup(argv[2]);
30      data.size = strlen(argv[2]);
31
32      if((ret = dbp->put(dbp,NULL,&key,&data,0)) != 0) {
33              dbp->err(dbp,ret,"dbp->put()");
34              dbp->close(dbp,0);
35              exit(1);
36      }
37      printf("Stored key %s, data %s\n",(char *)key.data,(char *)data.data);
38
39      memset(&data,0,sizeof(data));
40
41      if((ret = dbp->get(dbp,NULL,&key,&data,0)) != 0) {
42              dbp->err(dbp,ret,"dbp->get()");
43              exit(1);
44      }
45      printf("Retrieved key %s, data %s\n",(char *)key.data,(char *)data.data);
46
47      if((ret = dbp->del(dbp,NULL,&key,0)) != 0) {
48              dbp->err(dbp,ret,"dbp->del()");
49              exit(1);
50      }
51      dbp->close(dbp,0);
52      return(0);
53   }

Prev

Next