Postgres：为不相关的表选择块插入

Question

我们目前正面临一些数据库 (postgres) 问题，并且已经到了我们所拥有的信息无法带来新见解的地步。希望有人可以在这里帮助我们。

一些背景

我们正在开发的工具基本上是一个通用数据库系统。因此用户可以动态添加表和列。 将条目插入其中一个表后，我们返回条目的“完整”版本。例如，如果条目包含一个用户列（表示为用户 ID 数组），我们会查询有关这些用户的一些信息并将其添加到条目中，然后再发送给客户端。添加信息是使用 JavaScript 而不是通过 JOIN 完成的。

问题

users 表上的 SELECT 查询似乎在某些生成的表上阻塞了 INSERT。两个表之间没有外键关系（条目内的用户 ID 存储为整数数组）。 此外，插入似乎相互阻塞。但也许这是由第一个问题引起的？

为了查看哪些查询阻塞了哪些其他查询，我们运行了以下语句：

SELECT 
    blockeda.pid AS blocked_pid,
    blockeda.query as blocked_query,
    blockinga.pid AS blocking_pid,
    blockinga.query as blocking_query,
    blockedl.mode as blocked_mode,
    blockeda.query_start as blocked_query_start,
    blockinga.query_start as blocking_query_start
FROM 
    pg_catalog.pg_locks blockedl
JOIN 
    pg_stat_activity blockeda 
ON 
    blockedl.pid = blockeda.pid
JOIN 
    pg_catalog.pg_locks blockingl
ON
    (blockingl.transactionid=blockedl.transactionid AND blockedl.pid != blockingl.pid)
JOIN 
    pg_stat_activity blockinga 
ON 
    blockingl.pid = blockinga.pid
WHERE NOT 
    blockedl.granted
LIMIT
    10;

结果如下所示（除了我稍微更改了表名和列名）：

 blocked_pid |                                                                                                                                                                                             blocked_query                                                                                                                 | blocking_pid |                                                                                                                                                                                            blocking_query                                                                                                                 | blocked_mode |      blocked_query_start      |     blocking_query_start      
-------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
       96170 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99736 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:41:07.707156+00 | 2017-12-13 15:40:27.217027+00
       96341 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99033 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:39:04.585587+00 | 2017-12-13 15:13:19.079758+00
       96341 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99427 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:39:04.585587+00 | 2017-12-13 15:13:27.534743+00
       96341 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99439 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:39:04.585587+00 | 2017-12-13 15:13:22.371772+00
       96667 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99127 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:39:00.840949+00 | 2017-12-13 15:36:17.303978+00
       96667 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        97108 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:39:00.840949+00 | 2017-12-13 15:36:35.485022+00
       96667 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        96822 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:39:00.840949+00 | 2017-12-13 15:38:57.932188+00
       96677 | insert into "generated_table_2" ("generated_column_2_searchText", "generated_column_2_text", "generated_column_5_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        96338 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:12:22.040108+00 | 2017-12-13 15:11:36.813946+00
       96822 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99127 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:38:57.932188+00 | 2017-12-13 15:36:17.303978+00
       96822 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        96667 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:38:57.932188+00 | 2017-12-13 15:39:00.840949+00
       96822 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        97108 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:38:57.932188+00 | 2017-12-13 15:36:35.485022+00
       97110 | insert into "generated_table_3" ("generated_column_3_searchText", "generated_column_3_text", "generated_column_3_textType", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning *   |        96422 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:47:12.530821+00 | 2017-12-13 15:42:08.271596+00
       97108 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99127 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:36:35.485022+00 | 2017-12-13 15:36:17.303978+00
       97108 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        96667 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:36:35.485022+00 | 2017-12-13 15:39:00.840949+00
       97108 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        96822 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:36:35.485022+00 | 2017-12-13 15:38:57.932188+00
       99427 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99033 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:13:27.534743+00 | 2017-12-13 15:13:19.079758+00
       99427 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99439 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:13:27.534743+00 | 2017-12-13 15:13:22.371772+00
       99427 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        96341 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:13:27.534743+00 | 2017-12-13 15:39:04.585587+00
       99439 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99033 | select "id", "display_name", "user_name", "initials", "image_link", "is_image_preferred" from "users" where "id" in ($1) and "deprecated_at" is null                                                                                                                                                                      | ShareLock    | 2017-12-13 15:13:22.371772+00 | 2017-12-13 15:13:19.079758+00
       99439 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        99427 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:13:22.371772+00 | 2017-12-13 15:13:27.534743+00
       99439 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * |        96341 | insert into "generated_table_1" ("generated_column_1_searchText", "generated_column_1_text", "generated_column_4_categories", "created_at", "created_by", "display_string", "listId", "shortId", "sort_order", "updated_at", "updated_by", "uuid") values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) returning * | ShareLock    | 2017-12-13 15:13:22.371772+00 | 2017-12-13 15:39:04.585587+00

有谁知道为什么这些查询应该相互阻止？ 如果您需要更多信息来回答问题，请告诉我。

任何帮助将不胜感激！

非常感谢，

杰西

编辑

生成表的表定义（静态部分）：

id: integer
shortId: character varying(255)
uuid: uuid
display_string: text
sort_order: numeric
parent_id: integer
created_by: integer
updated_by: integer
deprecated_by: integer 
created_at: timestamp with time zone
updated_at: timestamp with time zone
deprecated_at: timestamp with time zone

解决方法

通过手动终止任何运行时间超过 30 秒的事务，我们暂时解决了这个问题。似乎只有少数交易从未解决，因此越来越多的新交易被阻止并堆积起来。

之后，我们将启动这些事务的相关代码更改为使用 Promise 而不是回调，从此错误不再发生。所以也许我们忘记在其中一种错误情况下调用回调。 我们将进一步调查，看看这是否真的解决了这个问题。感谢您一直以来的帮助！

Answer 1

您正在运行的查询返回阻塞事务运行的 最新 语句，但这不一定是导致锁定的语句（在 SELECT 的情况下，它很可能不是）。

首先要弄清楚实际运行的是哪些 SQL 语句。

您可以设置log_statements='all' 并重现问题。
确保 log_line_prefix 包含 %c 以便您可以识别会话。
然后找出每个涉及的事务运行的语句。

请记住，如果涉及外键或触发器，看似无关的表可能会被语句锁定。