Truncate and insert new content into table with the least amount of interruption









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Twice a day, I run a heavy query and save the results (40MBs worth of rows) to a table.



I truncate this results table before inserting the new results such that it only ever has the latest query's results in it.



The problem, is that while the update to the table is written, there is technically no data and/or a lock. When that is the case, anyone interacting with the site could experience an interruption. I haven't experienced this yet, but I am looking to mitigate this in the future.



What is the best way to remedy this? Is it proper to write the new results to a table named results_pending, then drop the results table and rename results_pending to results?










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    up vote
    2
    down vote

    favorite












    Twice a day, I run a heavy query and save the results (40MBs worth of rows) to a table.



    I truncate this results table before inserting the new results such that it only ever has the latest query's results in it.



    The problem, is that while the update to the table is written, there is technically no data and/or a lock. When that is the case, anyone interacting with the site could experience an interruption. I haven't experienced this yet, but I am looking to mitigate this in the future.



    What is the best way to remedy this? Is it proper to write the new results to a table named results_pending, then drop the results table and rename results_pending to results?










    share|improve this question























      up vote
      2
      down vote

      favorite









      up vote
      2
      down vote

      favorite











      Twice a day, I run a heavy query and save the results (40MBs worth of rows) to a table.



      I truncate this results table before inserting the new results such that it only ever has the latest query's results in it.



      The problem, is that while the update to the table is written, there is technically no data and/or a lock. When that is the case, anyone interacting with the site could experience an interruption. I haven't experienced this yet, but I am looking to mitigate this in the future.



      What is the best way to remedy this? Is it proper to write the new results to a table named results_pending, then drop the results table and rename results_pending to results?










      share|improve this question













      Twice a day, I run a heavy query and save the results (40MBs worth of rows) to a table.



      I truncate this results table before inserting the new results such that it only ever has the latest query's results in it.



      The problem, is that while the update to the table is written, there is technically no data and/or a lock. When that is the case, anyone interacting with the site could experience an interruption. I haven't experienced this yet, but I am looking to mitigate this in the future.



      What is the best way to remedy this? Is it proper to write the new results to a table named results_pending, then drop the results table and rename results_pending to results?







      sql sql-server






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      asked Nov 9 at 21:09









      Matt

      9,65653160269




      9,65653160269






















          2 Answers
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          Two methods come to mind. One is to swap partitions for the table. To be honest, I haven't done this in SQL Server, but it should work at a low level.



          I would normally have all access go through a view. Then, I would create the new day's data in a separate table -- and change the view to point to the new table. The view change is close to "atomic". Well, actually, there is a small period of time when the view might not be available.



          Then, at your leisure you can drop the old version of the table.






          share|improve this answer



























            up vote
            1
            down vote













            TRUNCATE is a DDL operation which causes problems like this. If you are using snapshot isolation with row versioning and want users to either see the old or new data then use a single transaction to DELETE the old records and INSERT the new data.



            Another option if a lot of the data doesn't actually change is to UPDATE / INSERT / DELETE only those records that need it and leave unchanged records alone.






            share|improve this answer




















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              2 Answers
              2






              active

              oldest

              votes








              2 Answers
              2






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes








              up vote
              2
              down vote



              accepted










              Two methods come to mind. One is to swap partitions for the table. To be honest, I haven't done this in SQL Server, but it should work at a low level.



              I would normally have all access go through a view. Then, I would create the new day's data in a separate table -- and change the view to point to the new table. The view change is close to "atomic". Well, actually, there is a small period of time when the view might not be available.



              Then, at your leisure you can drop the old version of the table.






              share|improve this answer
























                up vote
                2
                down vote



                accepted










                Two methods come to mind. One is to swap partitions for the table. To be honest, I haven't done this in SQL Server, but it should work at a low level.



                I would normally have all access go through a view. Then, I would create the new day's data in a separate table -- and change the view to point to the new table. The view change is close to "atomic". Well, actually, there is a small period of time when the view might not be available.



                Then, at your leisure you can drop the old version of the table.






                share|improve this answer






















                  up vote
                  2
                  down vote



                  accepted







                  up vote
                  2
                  down vote



                  accepted






                  Two methods come to mind. One is to swap partitions for the table. To be honest, I haven't done this in SQL Server, but it should work at a low level.



                  I would normally have all access go through a view. Then, I would create the new day's data in a separate table -- and change the view to point to the new table. The view change is close to "atomic". Well, actually, there is a small period of time when the view might not be available.



                  Then, at your leisure you can drop the old version of the table.






                  share|improve this answer












                  Two methods come to mind. One is to swap partitions for the table. To be honest, I haven't done this in SQL Server, but it should work at a low level.



                  I would normally have all access go through a view. Then, I would create the new day's data in a separate table -- and change the view to point to the new table. The view change is close to "atomic". Well, actually, there is a small period of time when the view might not be available.



                  Then, at your leisure you can drop the old version of the table.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Nov 9 at 21:14









                  Gordon Linoff

                  745k32285390




                  745k32285390






















                      up vote
                      1
                      down vote













                      TRUNCATE is a DDL operation which causes problems like this. If you are using snapshot isolation with row versioning and want users to either see the old or new data then use a single transaction to DELETE the old records and INSERT the new data.



                      Another option if a lot of the data doesn't actually change is to UPDATE / INSERT / DELETE only those records that need it and leave unchanged records alone.






                      share|improve this answer
























                        up vote
                        1
                        down vote













                        TRUNCATE is a DDL operation which causes problems like this. If you are using snapshot isolation with row versioning and want users to either see the old or new data then use a single transaction to DELETE the old records and INSERT the new data.



                        Another option if a lot of the data doesn't actually change is to UPDATE / INSERT / DELETE only those records that need it and leave unchanged records alone.






                        share|improve this answer






















                          up vote
                          1
                          down vote










                          up vote
                          1
                          down vote









                          TRUNCATE is a DDL operation which causes problems like this. If you are using snapshot isolation with row versioning and want users to either see the old or new data then use a single transaction to DELETE the old records and INSERT the new data.



                          Another option if a lot of the data doesn't actually change is to UPDATE / INSERT / DELETE only those records that need it and leave unchanged records alone.






                          share|improve this answer












                          TRUNCATE is a DDL operation which causes problems like this. If you are using snapshot isolation with row versioning and want users to either see the old or new data then use a single transaction to DELETE the old records and INSERT the new data.



                          Another option if a lot of the data doesn't actually change is to UPDATE / INSERT / DELETE only those records that need it and leave unchanged records alone.







                          share|improve this answer












                          share|improve this answer



                          share|improve this answer










                          answered Nov 9 at 21:22









                          Brian

                          2,9091114




                          2,9091114



























                               

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