Re: waiting for client write

[Ayub Khan <ayub.hp@xxxxxxxxx>]

Would it be a cursor issue on postgres, as there seems to be a difference in how cursors are handled in postgres and Oracle database. It seems cursors are returned as buffers to the client side. Below are the steps we take from jdbc side

below is the stored procedure code:

CREATE OR REPLACE PROCEDURE ."menu_pkg$get_menu_items_p_new"(
i_restaurant_id bigint,
i_category_id bigint,
i_check_availability text,
i_branch_id bigint,
INOUT o_items refcursor,
INOUT o_combo refcursor)
LANGUAGE 'plpgsql'

AS $BODY$

BEGIN

    OPEN o_items FOR

        SELECT

            a.menu_item_id, a.menu_item_name, a.menu_item_category_id, b.menu_item_category_desc, c.menu_item_variant_id, c.menu_item_variant_type_id, c.price, c.size_id, c.parent_menu_item_variant_id, d.menu_item_variant_type_desc, e.size_desc, f.currency_code, a.image, a.mark_id, m.mark_name

        FROM .menu_item_category AS b, .menu_item_variant AS c, .menu_item_variant_type AS d, .item_size AS e, .restaurant AS f, .menu_item AS a

          LEFT OUTER JOIN .mark AS m  ON (a.mark_id = m.mark_id) WHERE a.menu_item_category_id = b.menu_item_category_id AND a.menu_item_id = c.menu_item_id
          AND c.menu_item_variant_type_id = d.menu_item_variant_type_id AND d.is_hidden = 'false' AND c.size_id = e.size_id AND a.restaurant_id = f.restaurant_id AND f.restaurant_id = i_restaurant_id AND (a.menu_item_category_id = i_category_id OR i_category_id IS NULL) AND c.menu_item_variant_id =
        (SELECT MIN(menu_item_variant_id) FROM .menu_item_variant   WHERE menu_item_id = a.menu_item_id AND deleted = 'N') AND a.active = 'Y' AND (CONCAT_WS('', ',', a.hidden_branch_ids, ',') NOT LIKE CONCAT_WS('', '%,', i_branch_id, ',%') OR i_branch_id IS NULL) AND .is_menu_item_available(a.menu_item_id, i_check_availability) = 'Y'

        ORDER BY a.row_order, menu_item_id;

    OPEN o_combo FOR

        SELECT

            mc.*, f.currency_code, (CASE

                                        WHEN blob_id IS NOT NULL THEN 'Y'

                                        ELSE 'N'

            END) AS has_image

        FROM .menu_combo AS mc, .restaurant AS f

        WHERE mc.restaurant_id = i_restaurant_id AND active = 'Y' AND mc.restaurant_id = f.restaurant_id AND (menu_item_category_id = i_category_id OR i_category_id IS NULL)

        ORDER BY combo_id;

END;

$BODY$;

1. open connection
2. set  auto commit to false
3. create callable statement
4. execute the call
5. get the results
6. set autocommit to true
7. close the resultset,callable statement and connection

On Wed, Jun 9, 2021 at 5:47 PM Ayub Khan <ayub.hp@xxxxxxxxx> wrote:

attached is the screenshot of RDS performance insights for AWS and it shows high waiting client writes. The api performance is slow. I read that this might be due to IOPS on RDS. However we have 80k IOPS on this test RDS. 

Below is the query which is being load tested

SELECT

                       a.menu_item_id,
                       a.menu_item_name,
                       a.menu_item_category_id,
                       b.menu_item_category_desc,
                       c.menu_item_variant_id,
                       c.menu_item_variant_type_id,
                       c.price,
                       c.size_id,
                       c.parent_menu_item_variant_id,
                       d.menu_item_variant_type_desc,
                       e.size_desc,
                       f.currency_code,
                       a.image,
                       a.mark_id,
                       m.mark_name

                     FROM .menu_item_category AS b, .menu_item_variant AS c,
                       .menu_item_variant_type AS d, .item_size AS e, .restaurant AS f,
                       .menu_item AS a

                       LEFT OUTER JOIN .mark AS m
                         ON (a.mark_id = m.mark_id)

                     WHERE a.menu_item_category_id = b.menu_item_category_id AND a.menu_item_id = c.menu_item_id AND
                           c.menu_item_variant_type_id = d.menu_item_variant_type_id AND d.is_hidden = 'false' AND
                           c.size_id = e.size_id AND a.restaurant_id = f.restaurant_id AND f.restaurant_id = 1528 AND
                           (a.menu_item_category_id = NULL OR NULL IS NULL)

                           AND c.menu_item_variant_id = (SELECT min(menu_item_variant_id)
                                                         FROM .menu_item_variant
                                                         WHERE menu_item_id = a.menu_item_id AND deleted = 'N'
                                                         LIMIT 1) AND a.active = 'Y'
                           AND (CONCAT_WS('', ',', a.hidden_branch_ids, ',') NOT LIKE CONCAT_WS('', '%,4191,%') OR
                                NULL IS NULL)
   AND .is_menu_item_available(a.menu_item_id, 'Y') = 'Y'

   ORDER BY a.row_order, menu_item_id;

--Ayub

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Sun Certified Enterprise Architect 1.5
Sun Certified Java Programmer 1.4
Microsoft Certified Systems Engineer 2000
http://in.linkedin.com/pub/ayub-khan/a/811/b81

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