Please find below the last source code, I removed the check on the table
(NOT NULL on both sql_val and seq_inc)
sqlite> WITH T(i) AS (SELECT (1)i UNION ALL SELECT i+1 FROM T WHERE
i<1000000) INSERT INTO seq_test(seq_num) SELECT seq_nextval('seq1') from T;
Run Time: real 18.829 user 16.146103 sys 0.140401
I find that the performance is not that bad now.
Because of the performance (but I did not measure), I won't do the check on
the parameters, but I did put the same name for the seq_init for 2 or 3
parameters.
Now I would like to implement the seq_currval:
Oracle raises an exception because seq_nextval must be called at least one
time for the session
H2 returns init minus seq (making nextval returning the init value) => this
is also the trick I used so the update is simpler so more efficient
do you agree that we must use a variable mapping sequenceName => last
nextval
should I use a very simple structure (fixed sized array and O(n) access)?
or use a map? but then I would rather prefer to switch to C++, unless you
have a better idea?
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
void sp_seq_init(sqlite3_context *context, int argc, sqlite3_value **argv) {
int rc = 0;
sqlite3_stmt *stmt;
sqlite3 *db = sqlite3_context_db_handle(context);
const unsigned char* seq_name = sqlite3_value_text(argv[0]);
long seq_init_val = sqlite3_value_int64(argv[1]);
long seq_inc_val = argc < 3 ? 1 : sqlite3_value_int64(argv[2]);
rc = sqlite3_exec(db, "CREATE TABLE IF NOT EXISTS SP_SEQUENCE ( " \
" SEQ_NAME TEXT PRIMARY KEY, " \
" SEQ_VAL INTEGER, " \
" SEQ_INC INTEGER " \
" )", 0, 0, 0);
if( rc != SQLITE_OK ) {
sqlite3_result_error(context, sqlite3_errmsg(db), -1);
return;
}
sqlite3_prepare_v2(db, "insert or replace into sp_sequence (seq_name,
seq_val, seq_inc) values (?, ?, ?)", -1, &stmt, 0);
sqlite3_bind_text(stmt, 1, seq_name, -1, SQLITE_STATIC);
sqlite3_bind_int64(stmt, 2, seq_init_val-seq_inc_val);
sqlite3_bind_int64(stmt, 3, seq_inc_val);
rc = sqlite3_step(stmt);
sqlite3_finalize(stmt);
if (rc != SQLITE_DONE) {
sqlite3_result_error(context, sqlite3_errmsg(db), -1);
return;
}
sqlite3_result_int64( context, seq_init_val );
}
void sp_seq_nextval(sqlite3_context *context, int argc, sqlite3_value
**argv) {
int rc = 0;
sqlite3_stmt *stmt;
sqlite3 *db = sqlite3_context_db_handle(context);
long seq_val = 0;
const unsigned char* seq_name = sqlite3_value_text(argv[0]);
sqlite3_prepare_v2(db, "update sp_sequence set seq_val = seq_val +
seq_inc where seq_name = ?", -1, &stmt, 0);
sqlite3_bind_text(stmt, 1, seq_name, -1, SQLITE_STATIC);
rc = sqlite3_step(stmt);
sqlite3_finalize(stmt);
if (rc != SQLITE_DONE) {
sqlite3_result_error(context, sqlite3_errmsg(db), -1);
return;
}
sqlite3_prepare_v2(db, "select seq_val from sp_sequence where seq_name =
?", -1, &stmt, 0);
sqlite3_bind_text(stmt, 1, seq_name, -1, SQLITE_STATIC);
rc = sqlite3_step(stmt);
if( rc == SQLITE_ROW) {
seq_val = sqlite3_column_int64(stmt, 0);
}
sqlite3_finalize(stmt);
if (rc != SQLITE_ROW) {
if( rc == SQLITE_DONE ) sqlite3_result_error(context, "sequence name
does not exist", -1);
else sqlite3_result_error(context, sqlite3_errmsg(db), -1);
return;
}
sqlite3_result_int64( context, seq_val );
}
int sqlite3_extension_init(
sqlite3 *db,
char **pzErrMsg,
const sqlite3_api_routines *pApi
){
SQLITE_EXTENSION_INIT2(pApi)
sqlite3_create_function(db, "seq_init", 3, SQLITE_UTF8, 0, sp_seq_init, 0,
0);
sqlite3_create_function(db, "seq_init", 2, SQLITE_UTF8, 0, sp_seq_init, 0,
0);
sqlite3_create_function(db, "seq_nextval", 1, SQLITE_UTF8, 0,
sp_seq_nextval, 0, 0);
return 0;
}
_______________________________________________
sqlite-users mailing list
[email protected]
http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
