env “TMPDIR" can't change the tmp store diretory

[runlilong]

my codes

package main

import (
	"database/sql"
	"log"
	"os"

	_ "github.com/mattn/go-sqlite3"
)

func main() {
	os.Setenv("TMPDIR", "/mnt/test")
	db, err := sql.Open("sqlite3", "db.bak")
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	_, err = db.Exec("VACUUM")
	if err != nil {
		log.Fatal("Failed to vacuum database:", err)
	} else {
		log.Println("Database vacuumed successfully")
	}
}

❯ du -d1 -h db.bak
84M     db.bak

❯ df -h
/dev/loop0              1003K  931K  1.0K 100% /mnt/test

the result of it

azTempDirs[0] = NULL
azTempDirs[1] = /mnt/test
2024/02/21 20:40:06 Database vacuumed successfully

while sqlite3 report the error

❯ export TMPDIR=/mnt/test
❯ sqlite3 db.bak -cmd "VACUUM" .quit

Error: database or disk is full

which says sqlite3 cli used the specified TMPDIR but the code didn't.

[mattn]

How about to use pragma?

PRAGMA temp_store_directory = '/path/to/the/tmpdir';

[runlilong]

still not work

❯ sqlite3 db.bak -cmd "PRAGMA temp_store_directory = '/mnt/test'; VACUUM" .quit

Error: database or disk is full

...
_, err = db.Exec("PRAGMA temp_store_directory = '/mnt/test'; VACUUM")
...

❯ go run main.go
azTempDirs[0] = NULL
azTempDirs[1] = /mnt/test
2024/02/21 21:17:54 Database vacuumed successfully

[mattn]

What is azTempDirs ?

[runlilong]

from https://raw.githubusercontent.com/mattn/go-sqlite3/master/sqlite3-binding.c. I add a print statement to confirm that it can access the env variable successfully.

/*
** Directories to consider for temp files.
*/
static const char *azTempDirs[] = {
  0,
  0,
  "/var/tmp",
  "/usr/tmp",
  "/tmp",
  "."
};

/*
** Initialize first two members of azTempDirs[] array.
*/
static void unixTempFileInit(void){
  azTempDirs[0] = getenv("SQLITE_TMPDIR");
  azTempDirs[1] = getenv("TMPDIR");
  printf("azTempDirs[0] = %s\n", azTempDirs[0] ? azTempDirs[0] : "NULL");
  printf("azTempDirs[1] = %s\n", azTempDirs[1] ? azTempDirs[1] : "NULL");
}

[mattn]

export SQLITE_TMPDIR=/mnt/test

How this work?

[runlilong]

SQLITE_TMPDIR doesn't work for both of them

[mattn]

$ ls -lah /data/nostr-relay.sqlite
-rw------- 1 mattn mattn 1.7G  2月 22 23:20 /data/nostr-relay.sqlite
$ sudo mkdir test
$ sudo chmod 600 test
$ TMPDIR=./test SQLITE_TMPDIR=./test sqlite3 /data/nostr-relay.sqlite -cmd vacuum .quit

This is succeeded. sqlite3 cli really look TMPDIR for vacuum?