Temporary sort file, Watch dog

[vvvait]

Hi. Thanks for adapting sqlite3 for esp32. I researched the work of the library for several months. On some requests, I began to receive the "disk I / O error" error. I got into the source and found that there is no way to create temporary files. in esp32.cpp: ESP32Open

const char *zName,              /* File to open, or 0 for a temp file */
...
if( zName==0 ){
  return SQLITE_IOERR;
}

i replaced return SQLITE_IOERR; to zName = "/sd/temp"; and selection of 1000 records with sorting began to work.

It is also worth adding feeding the WatchDog on requests longer than 3 seconds if execute worked in main loop task, otherwise it will fire, may by in ESP32Read and ESP32Write, or add some callbacks.

max performance i have with

define SQLITE_DEFAULT_PAGE_SIZE 512 //4096

define SQLITE_DEFAULT_CACHE_SIZE -8 // -1

[siara-cc]

Hi, Thank you very much for communicating your findings. I will incorporate these into the repo.

[vvvait]

Hi, you still need to delete the temporary file if it already exists, otherwise an error is displayed periodically that the database is damaged

if( zName==0 ){
    zName = "/sd/temp";
    remove(zName); 
}

[winkelict]

this might be a full implementation of temporary file support: https://github.com/siara-cc/esp32_arduino_sqlite3_lib/issues/81

[siara-cc]

@vvvait I have incorporated this with today's commit using code from @winkelict and @savejeff Thanks to all of you for the support!