sqlite3数据库加载到内存C ++并选择性能

Question

Is there any method to load sqlite3 database file from disk into memory before make any SELECTS on it? sqlite3_step() work really slow... So I want to load database into the memory to load the data quickly.

Before sqlite3 I use simple binary data serialization and all members of stackoverflow suggested to me to use sqlite3 for serialization and now my program is really slow.. so slow that I can not unserialize all my data. (Serialization work well with transactions)

Maybe also this will help. my SELECT : there are two selects and two sqlite3_step() on each unserialized object. queries looks like SELECT aaaa,bbb,ccc,ddd,eee,ggg,hhh,fff,jjj FROM table for two queries. First table with unique aaaa key, but second one not unique (so seems its without indexes at all)

UPDATE:

    // Create SQL statement
    std::string sql_createtable = "CREATE TABLE IF NOT EXISTS ssssssss(" \
        "sid INTEGER PRIMARY KEY     NOT NULL," \
        "last_access_time       INT     ," \
        "last_c_time        INT     ," \
        "total_c           INT     ," \
        "last_viewed_lid INT ," \
        "last_viewed_ltid INT     );";  
//      "showed TEXT     );";

    std::string sql_showed = "CREATE TABLE IF NOT EXISTS showed(" \
        "sid              INT     NOT NULL," \
        "rid              INT     ," \
        "lid         INT     ," \
        "ltid           INT         );";    

Select 1:

SELECT sid, last_access_time, last_c_time, total_c, last_viewed_lid, last_viewed_ltid FROM ssssss

Select 2:

"SELECT rid, lid, ltid FROM showed WHERE sid= ?1"; // sid is from first table. can be more than 1 the same sid

Hmm, seems the problem that sid at the second table showed is not unique and no index? How to add index to this statement ?

Maybe some other suggestions?

Answer 1

You want to add index. Since the column is not unique, you need to add it with separate command:

CREATE INDEX showed_sid ON showed (sid);

Just execute this right after creating the table.