Database error codes

The table below lists some popular errors that can be raised by Tarantool in case of various issues. You can find a complete list of errors in the errcode.h file.

Note

The box.error module provides the ability to get the information about the last error raised by Tarantool or raise custom errors manually.

Code	box.error value	Description
ER_NONMASTER	box.error.NONMASTER	(In replication) A server instance cannot modify data unless it is a master.
ER_ILLEGAL_PARAMS	box.error.ILLEGAL_PARAMS	Illegal parameters. Malformed protocol message.
ER_MEMORY_ISSUE	box.error.MEMORY_ISSUE	Out of memory: memtx_memory limit has been reached.
ER_WAL_IO	box.error.WAL_IO	Failed to write to disk. May mean: failed to record a change in the write-ahead log.
ER_READONLY	box.error.READONLY	Can’t modify data on a read-only instance.
ER_KEY_PART_COUNT	box.error.KEY_PART_COUNT	Key part count is not the same as index part count.
ER_NO_SUCH_SPACE	box.error.NO_SUCH_SPACE	The specified space does not exist.
ER_NO_SUCH_INDEX	box.error.NO_SUCH_INDEX	The specified index in the specified space does not exist.
ER_PROC_LUA	box.error.PROC_LUA	An error occurred inside a Lua procedure.
ER_FIBER_STACK	box.error.FIBER_STACK	The recursion limit was reached when creating a new fiber. This usually indicates that a stored procedure is recursively invoking itself too often.
ER_UPDATE_FIELD	box.error.UPDATE_FIELD	An error occurred during update of a field.
ER_TUPLE_FOUND	box.error.TUPLE_FOUND	A duplicate key exists in a unique index.

Handling errors

Here are some procedures that can make Lua functions more robust when there are errors, particularly database errors.

Invoke a function using pcall.

Take advantage of Lua’s mechanisms for Error handling and exceptions, particularly pcall. That is, instead of invoking with …
```
box.space.{space-name}:{function-name}()
```
… call the function as follows:
```
if pcall(box.space.{space-name}.{function-name}, box.space.{space-name}) ...
```
For some Tarantool box functions, pcall also returns error details, including a file-name and line-number within Tarantool’s source code. This can be seen by unpacking, for example:
```
status, error = pcall(function() box.schema.space.create('') end)
error:unpack()
```
See the tutorial Sum a JSON field for all tuples to see how pcall can fit in an application.
Examine errors and raise new errors using box.error.

To make a new error and pass it on, the box.error module provides box.error().

To find the last error, the box.error submodule provides box.error.last(). There is also a way to find the text of the last operating-system error for certain functions – errno.strerror([code]).
Log.

Put messages in a log using the log module.

Filter automatically generated messages using the log configuration parameter.

Generally, for Tarantool built-in functions which are designed to return objects: the result is an object, or nil, or a Lua error. For example consider the fio_read.lua program in a cookbook:

#!/usr/bin/env tarantool

local fio = require('fio')
local errno = require('errno')
local f = fio.open('/tmp/xxxx.txt', {'O_RDONLY' })
if not f then
    error("Failed to open file: "..errno.strerror())
end
local data = f:read(4096)
f:close()
print(data)

After a function call that might fail, like fio.open() above, it is common to see syntax like if not f then ... or if f == nil then ..., which check for common failures. But if there had been a syntax error, for example fio.opex instead of fio.open, then there would have been a Lua error and f would not have been changed. If checking for such an obvious error had been a concern, the programmer would probably have used pcall().

All functions in Tarantool modules should work this way, unless the manual explicitly says otherwise.

Version:

Database error codes

Handling errors