Redshift无LIMIT语句却报LIMIT语法错误的原因排查

运行以下SQL查询时反复失败：

with ssr as
 (select s_store_id,
        sum(sales_price) as sales,
        sum(profit) as profit,
        sum(return_amt) as returns,
        sum(net_loss) as profit_loss
 from
  ( select  ss_store_sk as store_sk,
            ss_sold_date_sk  as date_sk,
            ss_ext_sales_price as sales_price,
            ss_net_profit as profit,
            cast(0 as decimal(7,2)) as return_amt,
            cast(0 as decimal(7,2)) as net_loss
    from store_sales
    union all
    select json_data.sr_customer_sk::bigint as store_sk,
        sr_returned_date_sk as date_sk,
        cast(0 as decimal(7,2)) as sales_price,
        cast(0 as decimal(7,2)) as profit,
        json_data.sr_return_amt::decimal(7,2) as return_amt,
        json_data.sr_net_loss::decimal(7,2) as net_loss
    from store_returns_json
   ) salesreturns,
     date_dim,
     store
 where date_sk = d_date_sk
       and d_date between cast('1998-08-04' as date) 
                  and dateadd(day, 14, cast('1998-08-04' as date))
       and store_sk = s_store_sk
 group by s_store_id)
 ,
 csr as
 (select cp_catalog_page_id,
        sum(sales_price) as sales,
        sum(profit) as profit,
        sum(return_amt) as returns,
        sum(net_loss) as profit_loss
 from
  ( select  cs_catalog_page_sk as page_sk,
            cs_sold_date_sk  as date_sk,
            cs_ext_sales_price as sales_price,
            cs_net_profit as profit,
            cast(0 as decimal(7,2)) as return_amt,
            cast(0 as decimal(7,2)) as net_loss
    from catalog_sales
    union all
    select cr_catalog_page_sk as page_sk,
           cr_returned_date_sk as date_sk,
           cast(0 as decimal(7,2)) as sales_price,
           cast(0 as decimal(7,2)) as profit,
           cr_return_amount as return_amt,
           cr_net_loss as net_loss
    from catalog_returns
   ) salesreturns,
     date_dim,
     catalog_page
 where date_sk = d_date_sk
       and d_date between cast('1998-08-04' as date)
                  and dateadd(day, 14, cast('1998-08-04' as date))
       and page_sk = cp_catalog_page_sk
 group by cp_catalog_page_id)
 ,
 wsr as
 (select web_site_id,
        sum(sales_price) as sales,
        sum(profit) as profit,
        sum(return_amt) as returns,
        sum(net_loss) as profit_loss
 from
  ( select  ws_web_site_sk as wsr_web_site_sk,
            ws_sold_date_sk  as date_sk,
            ws_ext_sales_price as sales_price,
            ws_net_profit as profit,
            cast(0 as decimal(7,2)) as return_amt,
            cast(0 as decimal(7,2)) as net_loss
    from web_sales
    union all
    select ws_web_site_sk as wsr_web_site_sk,
           wr_returned_date_sk as date_sk,
           cast(0 as decimal(7,2)) as sales_price,
           cast(0 as decimal(7,2)) as profit,
           wr_return_amt as return_amt,
           wr_net_loss as net_loss
    from web_returns left outer join web_sales on
         ( wr_item_sk = ws_item_sk
           and wr_order_number = ws_order_number)
   ) salesreturns,
     date_dim,
     web_site
 where date_sk = d_date_sk
       and d_date between cast('1998-08-04' as date)
                  and dateadd(day, 14, cast('1998-08-04' as date))
       and wsr_web_site_sk = web_site_sk
 group by web_site_id)
select channel as xchannel
        , id as xid
        , sum(sales) as xsales
        , sum(returns) as xreturns
        , sum(profit) as xprofit
 from 
 (select 'store channel' as channel
        , 'store' || s_store_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from   ssr
 union all
 select 'catalog channel' as channel
        , 'catalog_page' || cp_catalog_page_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from  csr
 union all
 select 'web channel' as channel
        , 'web_site' || web_site_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from   wsr
 )
 group by (xchannel,xid)
  union all
  select channel as xchannel
        , 'All' as xid
        , sum(sales) as xsales
        , sum(returns) as xreturns
        , sum(profit) as xprofit
 from
(
 select 'store channel' as channel
        , 'store' || s_store_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from   ssr
 union all
 select 'catalog channel' as channel
        , 'catalog_page' || cp_catalog_page_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from  csr
 union all
 select 'web channel' as channel
        , 'web_site' || web_site_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from   wsr
)
 group by (xchannel)
 --order by xchannel,xid
 ;

报错信息：

Detail: SQL reparse error. Where: syntax error at or near "LIMIT"

问题原因 #

1. Redshift Serverless内部重解析bug：当处理包含多层CTE、UNION ALL且存在重复子查询的复杂语句时，Redshift Serverless的查询优化器会尝试自动添加LIMIT做预览解析，但这个内部操作会触发语法解析异常，即便代码里没有显式写LIMIT。
2. 匿名子查询的解析问题：原查询中最后两个UNION ALL对应的子查询没有指定别名，Redshift Serverless的解析器对这种匿名子查询的兼容性较差，容易触发解析错误。

修复方案 #

将重复的子查询逻辑提取为公共CTE，同时为所有子查询添加明确别名，简化查询结构：

with ssr as
 (select s_store_id,
        sum(sales_price) as sales,
        sum(profit) as profit,
        sum(return_amt) as returns,
        sum(net_loss) as profit_loss
 from
  ( select  ss_store_sk as store_sk,
            ss_sold_date_sk  as date_sk,
            ss_ext_sales_price as sales_price,
            ss_net_profit as profit,
            cast(0 as decimal(7,2)) as return_amt,
            cast(0 as decimal(7,2)) as net_loss
    from store_sales
    union all
    select json_data.sr_customer_sk::bigint as store_sk,
        sr_returned_date_sk as date_sk,
        cast(0 as decimal(7,2)) as sales_price,
        cast(0 as decimal(7,2)) as profit,
        json_data.sr_return_amt::decimal(7,2) as return_amt,
        json_data.sr_net_loss::decimal(7,2) as net_loss
    from store_returns_json
   ) salesreturns,
     date_dim,
     store
 where date_sk = d_date_sk
       and d_date between cast('1998-08-04' as date) 
                  and dateadd(day, 14, cast('1998-08-04' as date))
       and store_sk = s_store_sk
 group by s_store_id)
 ,
 csr as
 (select cp_catalog_page_id,
        sum(sales_price) as sales,
        sum(profit) as profit,
        sum(return_amt) as returns,
        sum(net_loss) as profit_loss
 from
  ( select  cs_catalog_page_sk as page_sk,
            cs_sold_date_sk  as date_sk,
            cs_ext_sales_price as sales_price,
            cs_net_profit as profit,
            cast(0 as decimal(7,2)) as return_amt,
            cast(0 as decimal(7,2)) as net_loss
    from catalog_sales
    union all
    select cr_catalog_page_sk as page_sk,
           cr_returned_date_sk as date_sk,
           cast(0 as decimal(7,2)) as sales_price,
           cast(0 as decimal(7,2)) as profit,
           cr_return_amount as return_amt,
           cr_net_loss as net_loss
    from catalog_returns
   ) salesreturns,
     date_dim,
     catalog_page
 where date_sk = d_date_sk
       and d_date between cast('1998-08-04' as date)
                  and dateadd(day, 14, cast('1998-08-04' as date))
       and page_sk = cp_catalog_page_sk
 group by cp_catalog_page_id)
 ,
 wsr as
 (select web_site_id,
        sum(sales_price) as sales,
        sum(profit) as profit,
        sum(return_amt) as returns,
        sum(net_loss) as profit_loss
 from
  ( select  ws_web_site_sk as wsr_web_site_sk,
            ws_sold_date_sk  as date_sk,
            ws_ext_sales_price as sales_price,
            ws_net_profit as profit,
            cast(0 as decimal(7,2)) as return_amt,
            cast(0 as decimal(7,2)) as net_loss
    from web_sales
    union all
    select ws_web_site_sk as wsr_web_site_sk,
           wr_returned_date_sk as date_sk,
           cast(0 as decimal(7,2)) as sales_price,
           cast(0 as decimal(7,2)) as profit,
           wr_return_amt as return_amt,
           wr_net_loss as net_loss
    from web_returns left outer join web_sales on
         ( wr_item_sk = ws_item_sk
           and wr_order_number = ws_order_number)
   ) salesreturns,
     date_dim,
     web_site
 where date_sk = d_date_sk
       and d_date between cast('1998-08-04' as date)
                  and dateadd(day, 14, cast('1998-08-04' as date))
       and wsr_web_site_sk = web_site_sk
 group by web_site_id),
-- 提取重复逻辑为公共CTE
channel_summary as (
 select 'store channel' as channel
        , 'store' || s_store_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from   ssr
 union all
 select 'catalog channel' as channel
        , 'catalog_page' || cp_catalog_page_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from  csr
 union all
 select 'web channel' as channel
        , 'web_site' || web_site_id as id
        , sales
        , returns
        , (profit - profit_loss) as profit
 from   wsr
)
-- 查询明细
select channel as xchannel
        , id as xid
        , sum(sales) as xsales
        , sum(returns) as xreturns
        , sum(profit) as xprofit
 from channel_summary
 group by (xchannel,xid)
  union all
-- 查询渠道汇总
select channel as xchannel
        , 'All' as xid
        , sum(sales) as xsales
        , sum(returns) as xreturns
        , sum(profit) as xprofit
 from channel_summary
 group by (xchannel)
 --order by xchannel,xid
 ;

额外建议 #

• 避免在Redshift Serverless中编写过于冗余的重复子查询，尽量通过公共CTE复用逻辑，降低查询复杂度。
• 如果仍出现类似解析错误，可以尝试将复杂查询拆分为多个步骤，先将中间结果存入临时表，再进行后续聚合查询。

内容的提问来源于stack exchange，提问作者Phil