Consulta detalhando diferenças entre linhas para uma grande quantidade de dados

Isso não vai ficar bonito, especialmente considerando as mais de 300 colunas e a indisponibilidade de LAG, nem é provável que tenha um desempenho muito bom, mas apenas como algo para começar, eu tentaria a seguinte abordagem:

• UNIONas duas tabelas.
• Para cada PK no conjunto combinado, obtenha sua "encarnação" anterior da tabela de arquivos (a implementação abaixo usa OUTER APPLY+ TOP (1)como um pobre homem LAG).
• Converta cada coluna de dados varchar(max)e desvire-os em pares, ou seja, o valor atual e o anterior ( CROSS APPLY (VALUES ...)funciona bem para esta operação).
• Por fim, filtre os resultados com base na diferença entre os valores em cada par.

O Transact-SQL do acima como eu vejo:

WITH
  Combined AS
  (
    SELECT * FROM dbo.bigtable
    UNION ALL
    SELECT * FROM dbo.bigtable_archive
  ) AS derived,
  OldAndNew AS
  (
    SELECT
      this.*,
      OldCol1 = last.Col1,
      OldCol2 = last.Col2,
      ...
    FROM
      Combined AS this
      OUTER APPLY
      (
        SELECT TOP (1)
          *
        FROM
          dbo.bigtable_archive
        WHERE
          PK = this.PK
          AND UpdateDate < this.UpdateDate
        ORDER BY
          UpdateDate DESC
      ) AS last
  )
SELECT
  t.PK,
  t.UpdateDate,
  x.ColumnName,
  x.OldValue,
  x.NewValue
FROM
  OldAndNew AS t
  CROSS APPLY
  (
    VALUES
    ('Col1', CAST(t.OldCol1 AS varchar(max), CAST(t.Col1 AS varchar(max))),
    ('Col2', CAST(t.OldCol2 AS varchar(max), CAST(t.Col2 AS varchar(max))),
    ...
  ) AS x (ColumnName, OldValue, NewValue)
WHERE
  NOT EXISTS (SELECT x.OldValue INTERSECT x.NewValue)
ORDER BY
  t.PK,
  t.UpdateDate,
  x.ColumnName
;

Se você não dinamizar os dados para uma tabela temporária

create table #T
(
  PK varchar(12) not null,
  UpdateDate datetime not null,
  ColumnName nvarchar(128) not null,
  Value varchar(max),
  Version int not null
);

Você pode combinar as linhas para encontrar o valor novo e antigo com uma autojunção em PK, ColumnNamee Version = Version + 1.

A parte não tão bonita é, é claro, fazer o unpivot de suas 300 colunas na tabela temporária das duas tabelas base.

XML para o resgate para tornar as coisas menos complicadas.

É possível desdinamizar dados com XML sem precisar saber quais colunas reais existem na tabela que serão desdinamizadas. Os nomes das colunas devem ser válidos como nomes de elementos em XML ou falharão.

A ideia é criar um XML para cada linha com todos os valores dessa linha.

select bt.PK,
       bt.UpdateDate,
       (select bt.* for xml path(''), elements xsinil, type) as X
from dbo.bigtable as bt;

<UpdateDate xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">2001-01-03T00:00:00</UpdateDate>
<PK xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">PK1</PK>
<col1 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">c1_1_3</col1>
<col2 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">3</col2>
<col3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:nil="true" />
<colN xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">2001-01-03T00:00:00</colN>

elements xsinilexiste para criar elementos para colunas com NULL.

O XML pode então ser fragmentado usando nodes('*') para obter uma linha para cada coluna e usar local-name(.)para obter o nome do elemento e text()obter o valor.

  select C1.PK,
         C1.UpdateDate,
         T.X.value('local-name(.)', 'nvarchar(128)') as ColumnName,
         T.X.value('text()[1]', 'varchar(max)') as Value
  from C1
    cross apply C1.X.nodes('row/*') as T(X)

Solução completa abaixo. Observe que Versionestá invertido. 0 = última versão.

create table #X
(
  PK varchar(12) not null,
  UpdateDate datetime not null,
  Version int not null,
  RowData xml not null
);

create table #T
(
  PK varchar(12) not null,
  UpdateDate datetime not null,
  ColumnName nvarchar(128) not null,
  Value varchar(max),
  Version int not null
);


insert into #X(PK, UpdateDate, Version, RowData)
select bt.PK,
       bt.UpdateDate,
       0,
       (select bt.* for xml path(''), elements xsinil, type)
from dbo.bigtable as bt
union all
select bt.PK,
       bt.UpdateDate,
       row_number() over(partition by bt.PK order by bt.UpdateDate desc),
       (select bt.* for xml path(''), elements xsinil, type)
from dbo.bigtable_archive as bt;

with C as 
(
  select X.PK,
         X.UpdateDate,
         X.Version,
         T.C.value('local-name(.)', 'nvarchar(128)') as ColumnName,
         T.C.value('text()[1]', 'varchar(max)') as Value
  from #X as X
    cross apply X.RowData.nodes('*') as T(C)
)
insert into #T (PK, UpdateDate, ColumnName, Value, Version)
select C.PK,
       C.UpdateDate,
       C.ColumnName,
       C.Value,
       C.Version
from C 
where C.ColumnName not in (N'PK', N'UpdateDate');

/*
option (querytraceon 8649);

The above query might need some trick to go parallel.
For the testdata I had on my machine exection time is 16 seconds vs 2 seconds
https://sqlkiwi.blogspot.com/2011/12/forcing-a-parallel-query-execution-plan.html
http://dataeducation.com/next-level-parallel-plan-forcing-an-alternative-to-8649/

*/

select New.PK,
       New.UpdateDate,
       New.ColumnName,
       Old.Value as OldValue,
       New.Value as NewValue
from #T as New
  left outer join #T as Old
    on Old.PK = New.PK and
       Old.ColumnName = New.ColumnName and
       Old.Version = New.Version + 1;

Sugiro outra abordagem.

Embora você não possa alterar o aplicativo atual, pode ser que você possa alterar o comportamento do banco de dados.

Se possível, adicionaria dois TRIGGERS nas tabelas atuais.

Um INSTEAD OF INSERT em dbo.bigtable_archive que adiciona o novo registro somente se ele não existir no momento.

CREATE TRIGGER dbo.IoI_BTA
ON dbo.bigtable_archive
INSTEAD OF INSERT
AS
BEGIN
    IF NOT EXISTs(SELECT 1 
                  FROM dbo.bigtable_archive bta
                  INNER JOIN inserted i
                  ON  bta.PK = i.PK
                  AND bta.UpdateDate = i.UpdateDate)
    BEGIN
        INSERT INTO dbo.bigtable_archive
        SELECT * FROM inserted;
    END
END

E um gatilho AFTER INSERT no bigtable que faz exatamente o mesmo trabalho, mas usando dados do bigtable.

CREATE TRIGGER dbo.IoI_BT
ON dbo.bigtable
AFTER INSERT
AS
BEGIN
    IF NOT EXISTS(SELECT 1 
                  FROM dbo.bigtable_archive bta
                  INNER JOIN inserted i
                  ON  bta.PK = i.PK
                  AND bta.UpdateDate = i.UpdateDate)
    BEGIN
        INSERT INTO dbo.bigtable_archive
        SELECT * FROM inserted;
    END
END

Ok, eu configurei um pequeno exemplo aqui com esses valores iniciais:

SELECT * FROM bigtable;
SELECT * FROM bigtable_archive;

UpdateData | PK | col1 | col2 | col3
:------------------ | :-- | :--- | ---: | :---
02/01/2017 00:00:00 | ABC | C3 | 1 | C1  

UpdateData | PK | col1 | col2 | col3
:------------------ | :-- | :--- | ---: | :---
01/01/2017 00:00:00 | ABC | C1 | 1 | C1  

Agora você deve inserir em bigtable_archive todos os registros pendentes do bigtable.

INSERT INTO bigtable_archive
SELECT *
FROM   bigtable
WHERE  UpdateDate >= '20170102';

SELECT * FROM bigtable_archive;
GO

UpdateData | PK | col1 | col2 | col3
:------------------ | :-- | :--- | ---: | :---
01/01/2017 00:00:00 | ABC | C1 | 1 | C1  
02/01/2017 00:00:00 | ABC | C3 | 1 | C1  

Agora, na próxima vez que o aplicativo tentar inserir um registro na tabela bigtable_archive, os gatilhos detectarão se ele existe e a inserção será evitada.

INSERT INTO dbo.bigtable_archive VALUES('20170102', 'ABC', 'C3', 1, 'C1');
GO

SELECT * FROM bigtable_archive;
GO

UpdateData | PK | col1 | col2 | col3
:------------------ | :-- | :--- | ---: | :---
01/01/2017 00:00:00 | ABC | C1 | 1 | C1  
02/01/2017 00:00:00 | ABC | C3 | 1 | C1  

Obviamente, agora você pode obter a linha do tempo das alterações consultando apenas a tabela de arquivos. E o aplicativo nunca perceberá que um gatilho está silenciosamente fazendo o trabalho nos bastidores.

dbfiddle aqui

Working proposal, w/ some sample data, can be found @ rextester: bigtable unpivot

The gist of the operation:

1 - Use syscolumns and for xml to dynamically generate our column lists for the unpivot operation; all values will be converted to varchar(max), w/ NULLs being converted to the string 'NULL' (this addresses issue with unpivot skipping NULL values)

2 - Generate a dynamic query to unpivot data into the #columns temp table

• Why a temp table vs CTE (via with clause)? concerned with potential performance issue for a large volume of data and a CTE self-join with no usable index/hashing scheme; a temp table allows for creation of an index which should improve performance on the self-join [ see slow CTE self join ]
• Data is written to #columns in PK+ColName+UpdateDate order, allowing us to store PK/Colname values in adjacent rows; an identity column (rid) allows us to self-join these consecutive rows via rid = rid + 1

3 - Perform a self join of the #temp table to generate the desired output

Cutting-n-pasting from rextester ...

Create some sample data and our #columns table:

CREATE TABLE dbo.bigtable
(UpdateDate datetime      not null
,PK         varchar(12)   not null
,col1       varchar(100)      null
,col2       int               null
,col3       varchar(20)       null
,col4       datetime          null
,col5       char(20)          null
,PRIMARY KEY (PK)
);

CREATE TABLE dbo.bigtable_archive
(UpdateDate datetime      not null
,PK         varchar(12)   not null
,col1       varchar(100)      null
,col2       int               null
,col3       varchar(20)       null
,col4       datetime          null
,col5       char(20)          null
,PRIMARY KEY (PK, UpdateDate)
);

insert into dbo.bigtable         values ('20170512', 'ABC', NULL, 6, 'C1', '20161223', 'closed')

insert into dbo.bigtable_archive values ('20170427', 'ABC', NULL, 6, 'C1', '20160820', 'open')
insert into dbo.bigtable_archive values ('20170315', 'ABC', NULL, 5, 'C1', '20160820', 'open')
insert into dbo.bigtable_archive values ('20170212', 'ABC', 'C1', 1, 'C1', '20160820', 'open')
insert into dbo.bigtable_archive values ('20170109', 'ABC', 'C1', 1, 'C1', '20160513', 'open')

insert into dbo.bigtable         values ('20170526', 'XYZ', 'sue', 23, 'C1', '20161223', 're-open')

insert into dbo.bigtable_archive values ('20170401', 'XYZ', 'max', 12, 'C1', '20160825', 'cancel')
insert into dbo.bigtable_archive values ('20170307', 'XYZ', 'bob', 12, 'C1', '20160825', 'cancel')
insert into dbo.bigtable_archive values ('20170223', 'XYZ', 'bob', 12, 'C1', '20160820', 'open')
insert into dbo.bigtable_archive values ('20170214', 'XYZ', 'bob', 12, 'C1', '20160513', 'open')
;

create table #columns
(rid        int           identity(1,1)
,PK         varchar(12)   not null
,UpdateDate datetime      not null
,ColName    varchar(128)  not null
,ColValue   varchar(max)      null
,PRIMARY KEY (rid, PK, UpdateDate, ColName)
);

The guts of the solution:

declare @columns_max varchar(max),
        @columns_raw varchar(max),
        @cmd         varchar(max)

select  @columns_max = stuff((select ',isnull(convert(varchar(max),'+name+'),''NULL'') as '+name
                from    syscolumns
                where   id   = object_id('dbo.bigtable')
                and     name not in ('PK','UpdateDate')
                order by name
                for xml path(''))
            ,1,1,''),
        @columns_raw = stuff((select ','+name
                from    syscolumns
                where   id   = object_id('dbo.bigtable')
                and     name not in ('PK','UpdateDate')
                order by name
                for xml path(''))
            ,1,1,'')


select @cmd = '
insert #columns (PK, UpdateDate, ColName, ColValue)
select PK,UpdateDate,ColName,ColValue
from
(select PK,UpdateDate,'+@columns_max+' from bigtable
 union all
 select PK,UpdateDate,'+@columns_max+' from bigtable_archive
) p
unpivot
  (ColValue for ColName in ('+@columns_raw+')
) as unpvt
order by PK, ColName, UpdateDate'

--select @cmd

execute(@cmd)

--select * from #columns order by rid
;

select  c2.PK, c2.UpdateDate, c2.ColName as ColumnName, c1.ColValue as 'Old Value', c2.ColValue as 'New Value'
from    #columns c1,
        #columns c2
where   c2.rid                       = c1.rid + 1
and     c2.PK                        = c1.PK
and     c2.ColName                   = c1.ColName
and     isnull(c2.ColValue,'xxx')   != isnull(c1.ColValue,'xxx')
order by c2.UpdateDate, c2.PK, c2.ColName
;

And the results:

Note: apologies ... couldn't figure out an easy way to cut-n-paste the rextester output into a code block. I'm open to suggestions.

Potential issues/concerns:

1 - conversion of data to a generic varchar(max) can lead to loss of data precision which in turn can mean we miss some data changes; consider the following datetime and float pairs which, when converted/cast to the generic 'varchar(max)', lose their precision (ie, the converted values are the same):

original value       varchar(max)
-------------------  -------------------
06/10/2017 10:27:15  Jun 10 2017 10:27AM
06/10/2017 10:27:18  Jun 10 2017 10:27AM

    234.23844444                 234.238
    234.23855555                 234.238

    29333488.888            2.93335e+007
    29333499.999            2.93335e+007

While data precision could be maintained it would require a bit more coding (eg, casting based on source column datatypes); for now I've opted to stick with the generic varchar(max) per the OP's recommendation (and assumption that the OP knows the data well enough to know that we won't run into any issues of data precision loss).

2 - for really large sets of data we run the risk of blowing out some server resources, whether it be tempdb space and/or cache/memory; primary issue comes from the data explosion that occurs during an unpivot (eg, we go from 1 row and 302 pieces of data to 300 rows and 1200-1500 pieces of data, including 300 copies of the PK and UpdateDate columns, 300 column names)

Essa abordagem usa consulta dinâmica para gerar um sql para obter as alterações. O SP recebe um nome de tabela e esquema e fornece a saída desejada.

As suposições são de que as colunas PK e UpdateDate estejam presentes em todas as tabelas. E todas as tabelas de arquivo têm o formato originalTableName + "_archive"..

NB: Eu não verifiquei o desempenho.

NB: como isso usa sql dinâmico, devo adicionar uma advertência sobre injeção de segurança/sql. Restrinja o acesso ao SP e adicione outras validações para evitar injeção de sql.

    CREATE proc getTableChanges
    @schemaname  varchar(255),
    @tableName varchar(255)
    as

    declare @strg nvarchar(max), @colNameStrg nvarchar(max)='', @oldValueString nvarchar(max)='', @newValueString nvarchar(max)=''

    set @strg = '
    with cte as (

    SELECT  * , ROW_NUMBER() OVER(partition by PK ORDER BY UpdateDate) as RowNbr
    FROM    (

        SELECT  *
        FROM    [' + @schemaname + '].[' + @tableName + ']

        UNION

        SELECT  *
        FROM    [' + @schemaname + '].[' + @tableName + '_archive]

        ) a

    )
    '


    SET @strg = @strg + '

    SELECT  a.pk, a.updateDate, 
    CASE '

    DECLARE @colName varchar(255)
    DECLARE cur CURSOR FOR
        SELECT  COLUMN_NAME
        FROM    INFORMATION_SCHEMA.COLUMNS
        WHERE TABLE_SCHEMA = @schemaname
        AND TABLE_NAME = @tableName
        AND COLUMN_NAME NOT IN ('PK', 'Updatedate')

    OPEN cur
    FETCH NEXT FROM cur INTO @colName 

    WHILE @@FETCH_STATUS = 0
    BEGIN

        SET @colNameStrg  = @colNameStrg  + ' when a.' + @colName + ' <> b.' + @colName + ' then ''' + @colName + ''' '
        SET @oldValueString = @oldValueString + ' when a.' + @colName + ' <> b.' + @colName + ' then cast(a.' + @colName + ' as varchar(max))'
        SET @newValueString = @newValueString + ' when a.' + @colName + ' <> b.' + @colName + ' then cast(b.' + @colName + ' as varchar(max))'


    FETCH NEXT FROM cur INTO @colName 
    END

    CLOSE cur
    DEALLOCATE cur


    SET @colNameStrg = @colNameStrg  + '    END as ColumnChanges '
    SET @oldValueString = 'CASE ' + @oldValueString + ' END as OldValue'
    SET @newValueString = 'CASE ' + @newValueString + ' END as NewValue'

    SET @strg = @strg + @colNameStrg + ',' + @oldValueString + ',' + @newValueString

    SET @strg = @strg + '
        FROM    cte a join cte b on a.PK = b.PK and a.RowNbr + 1 = b.RowNbr 
        ORDER BY  a.pk, a.UpdateDate
    '

    print @strg

    execute sp_executesql @strg


    go

Chamada de amostra:

exec getTableChanges 'dbo', 'bigTable'

I am using AdventureWorks2012`,Production.ProductCostHistory and Production.ProductListPriceHistory in my example.It may not be perfect history table example, "but script is able to put together the desire output and correct output".

     DECLARE @sql NVARCHAR(MAX)
    ,@columns NVARCHAR(Max)
    ,@table VARCHAR(200) = 'ProductCostHistory'
    ,@Schema VARCHAR(200) = 'Production'
    ,@Archivecolumns NVARCHAR(Max)
    ,@ColForUnpivot NVARCHAR(Max)
    ,@ArchiveColForUnpivot NVARCHAR(Max)
    ,@PKCol VARCHAR(200) = 'ProductID'
    ,@UpdatedCol VARCHAR(200) = 'modifiedDate'
    ,@Histtable VARCHAR(200) = 'ProductListPriceHistory'
SELECT @columns = STUFF((
            SELECT ',CAST(p.' + QUOTENAME(column_name) + ' AS VARCHAR(MAX)) AS ' + QUOTENAME(column_name)
            FROM information_schema.columns
            WHERE table_name = @table
                AND column_name NOT IN (
                    @PKCol
                    ,@UpdatedCol
                    )
            ORDER BY ORDINAL_POSITION
            FOR XML PATH('')
            ), 1, 1, '')
    ,@Archivecolumns = STUFF((
            SELECT ',CAST(p1.' + QUOTENAME(column_name) + ' AS VARCHAR(MAX)) AS ' + QUOTENAME('A_' + column_name)
            FROM information_schema.columns
            WHERE table_name = @Histtable
                AND column_name NOT IN (
                    @PKCol
                    ,@UpdatedCol
                    )
            ORDER BY ORDINAL_POSITION
            FOR XML PATH('')
            ), 1, 1, '')
    ,@ColForUnpivot = STUFF((
            SELECT ',' + QUOTENAME(column_name)
            FROM information_schema.columns
            WHERE table_name = @table
                AND column_name NOT IN (
                    @PKCol
                    ,@UpdatedCol
                    )
            ORDER BY ORDINAL_POSITION
            FOR XML PATH('')
            ), 1, 1, '')
    ,@ArchiveColForUnpivot = STUFF((
            SELECT ',' + QUOTENAME('A_' + column_name)
            FROM information_schema.columns
            WHERE table_name = @Histtable
                AND column_name NOT IN (
                    @PKCol
                    ,@UpdatedCol
                    )
            ORDER BY ORDINAL_POSITION
            FOR XML PATH('')
            ), 1, 1, '')

--SELECT @columns   ,@Archivecolumns    ,@ColForUnpivot
SET @sql = N' 
    SELECT ' + @PKCol + ', ColumnName,
            OldValue,NewValue,' + @UpdatedCol + '
    FROM    (  
    SELECT p.' + @PKCol + '
        ,p.' + @UpdatedCol + '
        ,' + @columns + '
        ,' + @Archivecolumns + '
    FROM ' + @Schema + '.' + @table + ' p
    left JOIN ' + @Schema + '.' + @Histtable + ' p1 ON p.' + @PKCol + ' = p1.' + @PKCol + '

  ) t
    UNPIVOT (
        OldValue
        FOR ColumnName in (' + @ColForUnpivot + ')
    ) up

     UNPIVOT (
        NewValue
        FOR ColumnName1 in (' + @ArchiveColForUnpivot + ')
    ) up1

--print @sql
EXEC (@sql)

Here in inner Select query consider p as Main Table and p1 as History table.In unpivot it is important to convert it into same type.

You can take any other table name with fewer column name to understand my script.Any Explanation need then ping me.