Re: [Tarantool-patches] [PATCH v2 09/15] sql: rework AVG()

[Vladislav Shpilevoy via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Thanks for the fixes!

> diff --git a/src/box/sql/func.c b/src/box/sql/func.c
> index 12a6a5a2c..b5f154fb1 100644
> --- a/src/box/sql/func.c
> +++ b/src/box/sql/func.c
> @@ -102,6 +102,54 @@ fin_total(struct sql_context *ctx)
>  		mem_copy_as_ephemeral(ctx->pOut, ctx->pMem);
>  }
>  
> +/** Implementation of the AVG() function. */
> +static void
> +step_avg(struct sql_context *ctx, int argc, struct Mem **argv)
> +{
> +	assert(argc == 1);
> +	(void)argc;
> +	assert(ctx->pMem->type == MEM_TYPE_NULL || mem_is_bin(ctx->pMem));
> +	if (argv[0]->type == MEM_TYPE_NULL)
> +		return;
> +	struct Mem *mem;
> +	uint32_t *count;
> +	if (ctx->pMem->type == MEM_TYPE_NULL) {
> +		uint32_t size = sizeof(struct Mem) + sizeof(uint32_t);
> +		mem = sqlDbMallocRawNN(sql_get(), size);

1. Where is it deleted? Can't find.

> +		if (mem == NULL) {
> +			ctx->is_aborted = true;
> +			return;
> +		}
> +		count = (uint32_t *)(mem + 1);
> +		mem_create(mem);
> +		*count = 1;
> +		mem_copy_as_ephemeral(mem, argv[0]);
> +		mem_set_bin_allocated(ctx->pMem, (char *)mem, size);
> +		return;
> +	}
> diff --git a/test/sql-tap/built-in-functions.test.lua b/test/sql-tap/built-in-functions.test.lua
> index 507d06549..08a63b86d 100755
> --- a/test/sql-tap/built-in-functions.test.lua
> +++ b/test/sql-tap/built-in-functions.test.lua
> @@ -605,4 +605,33 @@ test:do_execsql_test(
>      }
>  )
>  
> +-- Make sure AVG() accepts and returns DOUBLE by default.
> +test:do_test(
> +    "builtins-4.1.1",
> +    function()
> +        return box.execute([[SELECT AVG(?);]], {1}).metadata
> +    end, {
> +        {name = "COLUMN_1", type = "double"},
> +    })
> +
> +test:do_test(
> +    "builtins-4.1.2",
> +    function()
> +        local res = {pcall(box.execute, [[SELECT AVG(?);]], {-1ULL})}
> +        return {tostring(res[3])}
> +    end, {
> +        "Type mismatch: can not convert integer(18446744073709551615) to double"
> +    })
> +
> +-- Make sure AVG() works with DECIMAL properly.
> +test:do_execsql_test(
> +    "builtins-4.1.3",
> +    [[
> +        SELECT AVG(cast(column_2 as DECIMAL)) from (values(1), (123.432));

2. I don't understand how does it work. Why not column_1? Why does it fail?

tarantool> box.execute('SELECT column_1 from (values(1), (123.432));')
---
- null
- Can’t resolve field 'COLUMN_1'
...

Isn't there 2 tuples [1], and [123.432] with just 1 column each?
And why does it work when I delete one of the values?

tarantool> box.execute('SELECT column_1 from (values(1));')
---
- metadata:
  - name: COLUMN_1
    type: integer
  rows:
  - [1]
...

> +    ]],
> +    {
> +        dec.new(62.216)
> +    }
> +)
> +
>  test:finish_test()
>