Re: [Tarantool-patches] [PATCH v2] tuple: make fields nullable by default except array/map

[Nikita Pettik <korablev@tarantool.org>]

On 13 Jul 15:36, Ilya Kosarev wrote:
> Since e1d3fe8ab8eed65394ad17409401a93b6fcdc435 (tuple format: don't
> allow null where array/map is expected) tuple fields are non-nullable
> by default. It seems strange at least in case we have implicit fields
> in front of explicit nullable field. Also it causes incorrect behaviour
> in case of using explicitly nullable array/map fields for multikey
> index.
> Now fields are nullable by default except arrays & maps, as far
> as their implicit nullability might break field accessors expectations,
> provide confusing error messages and cause incorrect behaviour of
> tuple_multikey_count(). In case explicitly nullable array/map fields
> are being used for multikey index, clear error message is provided.
> 
> Closes #5027
> ---
> diff --git a/src/box/memtx_space.c b/src/box/memtx_space.c
> index 875592026..8452ab430 100644
> --- a/src/box/memtx_space.c
> +++ b/src/box/memtx_space.c
> @@ -589,7 +589,9 @@ memtx_space_ephemeral_rowid_next(struct space *space, uint64_t *rowid)
>  static int
>  memtx_space_check_index_def(struct space *space, struct index_def *index_def)
>  {
> -	if (index_def->key_def->is_nullable) {
> +	struct key_def *key_def = index_def->key_def;

Hm, this change results in redundant diff below in this function.               
Mb better get rid of it?

> +	if (key_def->is_nullable) {
>  		if (index_def->iid == 0) {
>  			diag_set(ClientError, ER_NULLABLE_PRIMARY,
>  				 space_name(space));
> @@ -602,6 +604,14 @@ memtx_space_check_index_def(struct space *space, struct index_def *index_def)
>  			return -1;
>  		}
>  	}
> +	if (key_def->is_multikey &&
> +	    key_def->multikey_fieldno < space->def->field_count &&
> +	    space->def->fields[key_def->multikey_fieldno].is_nullable) {
> +		diag_set(ClientError, ER_UNSUPPORTED,
> +			 "multikey index",
> +			 "nullable root field");
> +		return -1;
> +	}

Consider refactoring:

@@ -607,9 +606,8 @@ memtx_space_check_index_def(struct space *space, struct index_def *index_def)
        if (key_def->is_multikey &&                                             
            key_def->multikey_fieldno < space->def->field_count &&              
            space->def->fields[key_def->multikey_fieldno].is_nullable) {        
-               diag_set(ClientError, ER_UNSUPPORTED,                           
-                        "multikey index",                                      
-                        "nullable root field");                                
+               diag_set(ClientError, ER_UNSUPPORTED, "multikey index",         
+                       "nullable root field");                                 
                return -1;                                                      
        }      

Moreover, I suggest moving this check to a separate patch.
See comments below.

> diff --git a/src/box/tuple_format.c b/src/box/tuple_format.c
> index 68ec2a749..8cb9be8bb 100644
> --- a/src/box/tuple_format.c
> +++ b/src/box/tuple_format.c
> @@ -152,7 +152,7 @@ tuple_field_new(void)
>  	field->type = FIELD_TYPE_ANY;
>  	field->offset_slot = TUPLE_OFFSET_SLOT_NIL;
>  	field->coll_id = COLL_NONE;
> -	field->nullable_action = ON_CONFLICT_ACTION_DEFAULT;
> +	field->nullable_action = ON_CONFLICT_ACTION_NONE;
>  	field->multikey_required_fields = NULL;
>  	return field;
>  }
> @@ -242,6 +242,24 @@ tuple_field_ensure_child_compatibility(struct tuple_field *parent,
>  	return 0;
>  }
>  
> +/**
> + * Tuple fields are nullable by default. However, it is not ok
> + * for array/map fields, as far as their implicit nullability
> + * might break field accessors expectations, provide confusing
> + * error messages and cause incorrect behaviour of
> + * tuple_multikey_count(). Thus array/map fields have to be

Is it only about _count() func? I mean mb it is easier to fix
that function, than update nullability during format creation?

> + * non-nullable by default, which means we have to update default
> + * nullability for them.
> + */
> +static void
> +tuple_field_update_nullability(struct tuple_field *field)
> +{
> +	if ((field->type == FIELD_TYPE_ARRAY ||
> +	     field->type == FIELD_TYPE_MAP) &&
> +	     tuple_field_is_nullable(field))
> +		field->nullable_action = ON_CONFLICT_ACTION_DEFAULT;
> +}

I don't like much name of this function...
Consider these variants:
tuple_field_set_composite_nullability()
tuple_field_update_composite_nullability()
tuple_field_update_compound_type_nullability()
...

Or smth like that


>  /**
>   * Given a field number and a path, add the corresponding field
>   * to the tuple format, allocating intermediate fields if
> @@ -317,11 +335,13 @@ tuple_format_add_field(struct tuple_format *format, uint32_t fieldno,
>  				parent->offset_slot = *current_slot;
>  			}
>  		}
> +		tuple_field_update_nullability(parent);
>  		parent->is_key_part = true;
>  		next->is_multikey_part = is_multikey;
>  		parent = next;
>  		token_count++;
>  	}
> +	tuple_field_update_nullability(parent);

I've commented this func call and all tests have been passed.
Please investigate why and either remove this call or provide
corresponding test.

>  	/*
>  	 * The path has already been verified by the
>  	 * key_def_decode_parts function.
> diff --git a/src/box/vinyl.c b/src/box/vinyl.c
> index fd9b7e6c0..32301d7ba 100644
> --- a/src/box/vinyl.c
> +++ b/src/box/vinyl.c
> @@ -651,13 +651,24 @@ vinyl_space_check_index_def(struct space *space, struct index_def *index_def)
>  			 index_def->name, space_name(space));
>  		return -1;
>  	}
> -	if (index_def->key_def->is_nullable && index_def->iid == 0) {
> +
> +	struct key_def *key_def = index_def->key_def;

Ditto: don't enlarge diff by introducing new var - it's not
reasonable here (IMHO).

> +	if (key_def->is_nullable && index_def->iid == 0) {
>  		diag_set(ClientError, ER_NULLABLE_PRIMARY, space_name(space));
>  		return -1;
>  	}
> +	if (key_def->is_multikey &&
> +	    key_def->multikey_fieldno < space->def->field_count &&
> +	    space->def->fields[key_def->multikey_fieldno].is_nullable) {
> +		diag_set(ClientError, ER_UNSUPPORTED,
> +		         "multikey index",
> +		         "nullable root field");
> +		return -1;
> +	}

Same check. Mb worth moving it to a helper? At least let's format
it properly.

>  	/* Check that there are no ANY, ARRAY, MAP parts */
> -	for (uint32_t i = 0; i < index_def->key_def->part_count; i++) {
> -		struct key_part *part = &index_def->key_def->parts[i];
> +	for (uint32_t i = 0; i < key_def->part_count; i++) {
> +		struct key_part *part = &key_def->parts[i];
>  		if (part->type <= FIELD_TYPE_ANY ||
>  		    part->type >= FIELD_TYPE_ARRAY) {
>  			diag_set(ClientError, ER_MODIFY_INDEX,
> @@ -667,7 +678,7 @@ vinyl_space_check_index_def(struct space *space, struct index_def *index_def)
>  			return -1;
>  		}
>  	}
> -	if (index_def->key_def->for_func_index) {
> +	if (key_def->for_func_index) {
>  		diag_set(ClientError, ER_UNSUPPORTED, "Vinyl",
>  			 "functional index");
>  		return -1;
> diff --git a/test/engine/gh-5027-fields-nullability.result b/test/engine/gh-5027-fields-nullability.result

Nit: mb gh-5027-extra-fields-nullability or gh-5027-compound-field-type-nullability?
Then others would understand what this test is about with ease.

> new file mode 100644
> index 000000000..1121727f6
> --- /dev/null
> +++ b/test/engine/gh-5027-fields-nullability.result
> @@ -0,0 +1,119 @@
> +-- test-run result file version 2
> index 000000000..960103d6c
> --- /dev/null
> +++ b/test/engine/gh-5027-fields-nullability.test.lua
> @@ -0,0 +1,37 @@
> +test_run = require('test_run').new()
> +s = box.schema.space.create('gh-5027', {engine=test_run:get_cfg('engine')})
> +_ = s:create_index('i1', {parts={{1, 'unsigned'}}})
> +_ = s:create_index('i2', {parts={{5, 'unsigned', is_nullable=true}}})
> +s:replace{1}
> +s:replace{1, box.NULL}
> +s:replace{1, box.NULL, box.NULL}
> +s:replace{1, box.NULL, box.NULL, box.NULL}
> +s:drop()
> +
> +s = box.schema.space.create('gh-5027', {engine=test_run:get_cfg('engine')})
> +_ = s:create_index('i1', {parts={{1, 'unsigned'}}})
> +_ = s:create_index('i2', {parts={{5, 'unsigned', is_nullable=false}}})
> +s:replace{1}
> +s:replace{1, box.NULL}
> +s:replace{1, box.NULL, box.NULL}
> +s:replace{1, box.NULL, box.NULL, box.NULL}
> +s:replace{1, box.NULL, box.NULL, box.NULL, 5}
> +s:drop()

As I see these two cases are a bit different. In fact in your patch
you fix two independent problems. I suggest you to split them into
two separate patches/tests. Or provide solid arguments why we shouldn't
do so.

> +s = box.schema.space.create('gh-5027', {engine=test_run:get_cfg('engine')})
> +_ = s:format({{name='id'}, {name='data', type='array', is_nullable=true}})
> +_ = s:create_index('i1', {parts={{1, 'unsigned'}}})
> +s:replace{1, box.NULL}
> +_ = s:create_index('i2', {parts={{field=2, path='[*].key', type='string'}}})
> +s:replace{2, box.NULL}
> +s:drop()
> +
> +s = box.schema.space.create('gh-5027', {engine=test_run:get_cfg('engine')})
> +_ = s:format({{name='id'}, {name='data', type='array'}})
> +_ = s:create_index('i1', {parts={{1, 'unsigned'}}})
> +s:replace{1, box.NULL}
> +_ = s:create_index('i2', {parts={{field=2, path='[*].key', type='string'}}})
> +s:replace{2, box.NULL}
> +s:replace{3, {}}
> +s:drop()
> -- 
> 2.17.1
>