Calculating total “on row” bytes for each row … the easy waySQL Database size doesn't match with the...

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Calculating total “on row” bytes for each row … the easy way


SQL Database size doesn't match with the total table sizes in the databaseDo you know an easy way to generate one record for each hour of the past 12 hours?Calculate number for each rowRunning total to the previous rowChoosing the right storage block size for sql serverCalculating Running Total After ResetSQL Server 2016 Maximum Bytes/RowWhat's the best way to iterate through the table to update a column in each row?sql server getting total for each groupSQL Server chooses Nested Loop join with dimensional table and make seek for each row













1















We want to calculate the total "on row" storage bytes for each row in the table. As we understand it, we must add up the DATALENGTH() of each column while also accounting for NULLs and things like VARCHAR(MAX) which only have a 24-byte pointer "on row". We are aware there is also some overhead for each row which is not accounted for in the query below.



SELECT   ROW_ID,

CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL1','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL1), 1)
END
+
CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL2','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL2), 1)
END
+
CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL3','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL3), 1)
END
+
...
...
AS ROW_SIZE

FROM EXAMPLE_TABLE

ORDER BY ROW_SIZE DESC
;


What a beast! And it's only an approximation.



Then we discovered



DBCC SHOWCONTIG ('EXAMPLE_TABLE') WITH TABLERESULTS


which returns MaximumRecordSize. This reveals that there is already an algorithm buried somewhere within SQL Server which is capable of calculating the exact size of a row.



How can we access that algorithm directly?










share|improve this question


















  • 3





    sys.dm_db_index_physical_stats is probably better to try working off of, especially since that DBCC command is deprecated.

    – LowlyDBA
    1 hour ago


















1















We want to calculate the total "on row" storage bytes for each row in the table. As we understand it, we must add up the DATALENGTH() of each column while also accounting for NULLs and things like VARCHAR(MAX) which only have a 24-byte pointer "on row". We are aware there is also some overhead for each row which is not accounted for in the query below.



SELECT   ROW_ID,

CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL1','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL1), 1)
END
+
CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL2','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL2), 1)
END
+
CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL3','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL3), 1)
END
+
...
...
AS ROW_SIZE

FROM EXAMPLE_TABLE

ORDER BY ROW_SIZE DESC
;


What a beast! And it's only an approximation.



Then we discovered



DBCC SHOWCONTIG ('EXAMPLE_TABLE') WITH TABLERESULTS


which returns MaximumRecordSize. This reveals that there is already an algorithm buried somewhere within SQL Server which is capable of calculating the exact size of a row.



How can we access that algorithm directly?










share|improve this question


















  • 3





    sys.dm_db_index_physical_stats is probably better to try working off of, especially since that DBCC command is deprecated.

    – LowlyDBA
    1 hour ago
















1












1








1








We want to calculate the total "on row" storage bytes for each row in the table. As we understand it, we must add up the DATALENGTH() of each column while also accounting for NULLs and things like VARCHAR(MAX) which only have a 24-byte pointer "on row". We are aware there is also some overhead for each row which is not accounted for in the query below.



SELECT   ROW_ID,

CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL1','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL1), 1)
END
+
CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL2','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL2), 1)
END
+
CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL3','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL3), 1)
END
+
...
...
AS ROW_SIZE

FROM EXAMPLE_TABLE

ORDER BY ROW_SIZE DESC
;


What a beast! And it's only an approximation.



Then we discovered



DBCC SHOWCONTIG ('EXAMPLE_TABLE') WITH TABLERESULTS


which returns MaximumRecordSize. This reveals that there is already an algorithm buried somewhere within SQL Server which is capable of calculating the exact size of a row.



How can we access that algorithm directly?










share|improve this question














We want to calculate the total "on row" storage bytes for each row in the table. As we understand it, we must add up the DATALENGTH() of each column while also accounting for NULLs and things like VARCHAR(MAX) which only have a 24-byte pointer "on row". We are aware there is also some overhead for each row which is not accounted for in the query below.



SELECT   ROW_ID,

CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL1','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL1), 1)
END
+
CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL2','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL2), 1)
END
+
CASE
WHEN COLUMNPROPERTY(OBJECT_ID('EXAMPLE_TABLE'),'COL3','PRECISION') = -1 THEN 24
ELSE ISNULL(DATALENGTH(COL3), 1)
END
+
...
...
AS ROW_SIZE

FROM EXAMPLE_TABLE

ORDER BY ROW_SIZE DESC
;


What a beast! And it's only an approximation.



Then we discovered



DBCC SHOWCONTIG ('EXAMPLE_TABLE') WITH TABLERESULTS


which returns MaximumRecordSize. This reveals that there is already an algorithm buried somewhere within SQL Server which is capable of calculating the exact size of a row.



How can we access that algorithm directly?







sql-server sql-server-2017 storage dbcc size






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 1 hour ago









UnLogicGuysUnLogicGuys

16218




16218








  • 3





    sys.dm_db_index_physical_stats is probably better to try working off of, especially since that DBCC command is deprecated.

    – LowlyDBA
    1 hour ago
















  • 3





    sys.dm_db_index_physical_stats is probably better to try working off of, especially since that DBCC command is deprecated.

    – LowlyDBA
    1 hour ago










3




3





sys.dm_db_index_physical_stats is probably better to try working off of, especially since that DBCC command is deprecated.

– LowlyDBA
1 hour ago







sys.dm_db_index_physical_stats is probably better to try working off of, especially since that DBCC command is deprecated.

– LowlyDBA
1 hour ago












1 Answer
1






active

oldest

votes


















4















How can we access that algorithm directly?




In so far as the answer to this question, specifically, you can't access it directly. There is nothing where you can say SELECT GetMeMaxRowSize(MyTable, MyPartition, MyIndex).



However, as LowlyDBA has pointed out, you can use sys.dm_db_index_physical_stats to give you more information than ShowContig. The quite interesting thing is that if you run DBCC SHOWCONTIG(), capturing deprecated information, you should see a message to use the aforementioned DMV in place of the ShowContig command.






share|improve this answer
























  • That's neat! Any idea if we'll see more explicit nudging around deprecated features, like said message, going forwards?

    – LowlyDBA
    59 mins ago











  • @LowlyDBA Unfortunately I do not, but we try to point people in the right direction :) If you think this should be updated or put anywhere in Docs, please let me know.

    – Sean Gallardy
    49 mins ago











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1 Answer
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active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









4















How can we access that algorithm directly?




In so far as the answer to this question, specifically, you can't access it directly. There is nothing where you can say SELECT GetMeMaxRowSize(MyTable, MyPartition, MyIndex).



However, as LowlyDBA has pointed out, you can use sys.dm_db_index_physical_stats to give you more information than ShowContig. The quite interesting thing is that if you run DBCC SHOWCONTIG(), capturing deprecated information, you should see a message to use the aforementioned DMV in place of the ShowContig command.






share|improve this answer
























  • That's neat! Any idea if we'll see more explicit nudging around deprecated features, like said message, going forwards?

    – LowlyDBA
    59 mins ago











  • @LowlyDBA Unfortunately I do not, but we try to point people in the right direction :) If you think this should be updated or put anywhere in Docs, please let me know.

    – Sean Gallardy
    49 mins ago
















4















How can we access that algorithm directly?




In so far as the answer to this question, specifically, you can't access it directly. There is nothing where you can say SELECT GetMeMaxRowSize(MyTable, MyPartition, MyIndex).



However, as LowlyDBA has pointed out, you can use sys.dm_db_index_physical_stats to give you more information than ShowContig. The quite interesting thing is that if you run DBCC SHOWCONTIG(), capturing deprecated information, you should see a message to use the aforementioned DMV in place of the ShowContig command.






share|improve this answer
























  • That's neat! Any idea if we'll see more explicit nudging around deprecated features, like said message, going forwards?

    – LowlyDBA
    59 mins ago











  • @LowlyDBA Unfortunately I do not, but we try to point people in the right direction :) If you think this should be updated or put anywhere in Docs, please let me know.

    – Sean Gallardy
    49 mins ago














4












4








4








How can we access that algorithm directly?




In so far as the answer to this question, specifically, you can't access it directly. There is nothing where you can say SELECT GetMeMaxRowSize(MyTable, MyPartition, MyIndex).



However, as LowlyDBA has pointed out, you can use sys.dm_db_index_physical_stats to give you more information than ShowContig. The quite interesting thing is that if you run DBCC SHOWCONTIG(), capturing deprecated information, you should see a message to use the aforementioned DMV in place of the ShowContig command.






share|improve this answer














How can we access that algorithm directly?




In so far as the answer to this question, specifically, you can't access it directly. There is nothing where you can say SELECT GetMeMaxRowSize(MyTable, MyPartition, MyIndex).



However, as LowlyDBA has pointed out, you can use sys.dm_db_index_physical_stats to give you more information than ShowContig. The quite interesting thing is that if you run DBCC SHOWCONTIG(), capturing deprecated information, you should see a message to use the aforementioned DMV in place of the ShowContig command.







share|improve this answer












share|improve this answer



share|improve this answer










answered 1 hour ago









Sean GallardySean Gallardy

16.2k22649




16.2k22649













  • That's neat! Any idea if we'll see more explicit nudging around deprecated features, like said message, going forwards?

    – LowlyDBA
    59 mins ago











  • @LowlyDBA Unfortunately I do not, but we try to point people in the right direction :) If you think this should be updated or put anywhere in Docs, please let me know.

    – Sean Gallardy
    49 mins ago



















  • That's neat! Any idea if we'll see more explicit nudging around deprecated features, like said message, going forwards?

    – LowlyDBA
    59 mins ago











  • @LowlyDBA Unfortunately I do not, but we try to point people in the right direction :) If you think this should be updated or put anywhere in Docs, please let me know.

    – Sean Gallardy
    49 mins ago

















That's neat! Any idea if we'll see more explicit nudging around deprecated features, like said message, going forwards?

– LowlyDBA
59 mins ago





That's neat! Any idea if we'll see more explicit nudging around deprecated features, like said message, going forwards?

– LowlyDBA
59 mins ago













@LowlyDBA Unfortunately I do not, but we try to point people in the right direction :) If you think this should be updated or put anywhere in Docs, please let me know.

– Sean Gallardy
49 mins ago





@LowlyDBA Unfortunately I do not, but we try to point people in the right direction :) If you think this should be updated or put anywhere in Docs, please let me know.

– Sean Gallardy
49 mins ago


















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