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The merge log is used to review customers that have been merged together, as well as including information about the merge. Merge Log Filters When the report loads, the default is to have the filters populate all merged customers from today’s date back to the same day of the previous month. How to merge log files TEMS DISCOVERY. The Merge-SPLogFile cmdlet returns records from Unified Logging Service (ULS) trace log files on each farm server that match the criteria, and writes the results to a new log file on the local computer. If no results are returned, a warning is written to the Windows PowerShell console window.
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MERGE statement was introduced in Oracle 9i to conditionally insert or update data depending on its presence, a process also known as an 'upsert'. The
MERGE statement reduces table scans and can perform the operation in parallel if required.
Consider the following example where data from the
HR_RECORDS table is merged into the
The source can also be a query.
MERGE statement is optimized for merging sets of data, rather than single rows, as shown in the example below.
Create the following test tables. The source table contains all the rows from the
ALL_OBJECTS view, while the destination table contains approximately half of the rows.
The following code compares the performance of four merge operations. The first uses the straight
MERGE statement. The second also uses the
MERGE statement, but in a row-by-row manner. The third performs an update, and conditionally inserts the row if the update touches zero rows. The fourth inserts the row, then performs an update if the insert fails with a duplicate value on index exception.
The output shows the straight
MERGE statement is an order of magnitude faster than its nearest rival. The update/insert performs almost twice the speed of the insert/update and even out performs the row-by-row
Just comparing the update/insert and the insert/update methods in isolation, we have to remember the comparisons will vary depending on the data in the table. If most of the data will not be present already, the insert/update approach may be better. If most of the data is already present, the update/insert approach will probably be better. If you are not sure, just use merge as it is clearer.
In addition to the straight
MERGE statement being faster, because it is a DML statement it can easily be run in parallel to improve performance further, provided your server can handle the extra load.
For more information see:
Merge Logitech Devices
Hope this helps. Regards Tim...