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Paginginfo

pauls0003
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Is there any more info available on how Paginginfo works within Appian ?

I've an upcoming use case where we will have a source of truth table which over time will become quite large. We will be doing all the user tricks to keep it responsive but at some point we will be querying it and no matter how many filters etc we get returned the data subset will be for a large amount of records. (let pretend 10,000).

i'll use pagingInfo to control the grid, but whilst I'm displaying records 1 to 100, what is happening to the rest of the data set ? I'm assuming it's floating around in Appian memory somewhere. 

I'm interested in people's thoughts here ?

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  • We routinely retrieve small subsets of data into a paging grid that ultimately comes from a much larger dataset. If you use a with() wrapped around your rule to retrieve data, and display your datasubset values somewhere while testing, this behavior becomes more clear.

    For example, your total dataset contains 500 items, but you only want to display (and keep in memory) 100 at a time. You set your paging info values to: startIndex:1, batchSize:100.

    You display your grid, if you display your datasubset in a paragraph field, you'll see three important values:
    datasubset.startIndex:1, datasubset.batchSize:100, datasubset.totalCount: 500,

    If you page your grid to the next one hundred and examine your values, you'll see:
    datasubset.startIndex:101, datasubset.batchSize:100, datasubset.totalCount:500

    In other words, it will retrieve values from 101 - 200 by taking the startIndex as the starting point and the batchSize as the amount to retrieve in this batch

    It is imperative that you use the value and saveInto of your pagingGrid to update the values used to retrieve the data from the database (or other datasource)

    From a performance perspective, if you are using a database backend and are retrieving these values from a table, consider the performance possibilities of Indexes, Partitions and even periodically materialized views to speed retrieval
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  • We routinely retrieve small subsets of data into a paging grid that ultimately comes from a much larger dataset. If you use a with() wrapped around your rule to retrieve data, and display your datasubset values somewhere while testing, this behavior becomes more clear.

    For example, your total dataset contains 500 items, but you only want to display (and keep in memory) 100 at a time. You set your paging info values to: startIndex:1, batchSize:100.

    You display your grid, if you display your datasubset in a paragraph field, you'll see three important values:
    datasubset.startIndex:1, datasubset.batchSize:100, datasubset.totalCount: 500,

    If you page your grid to the next one hundred and examine your values, you'll see:
    datasubset.startIndex:101, datasubset.batchSize:100, datasubset.totalCount:500

    In other words, it will retrieve values from 101 - 200 by taking the startIndex as the starting point and the batchSize as the amount to retrieve in this batch

    It is imperative that you use the value and saveInto of your pagingGrid to update the values used to retrieve the data from the database (or other datasource)

    From a performance perspective, if you are using a database backend and are retrieving these values from a table, consider the performance possibilities of Indexes, Partitions and even periodically materialized views to speed retrieval
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  • in reply to Richard

    Richard, It is very clear and to the point.  Thank you!  For some reason on my page, the paging grid is behaving bizarre!  I am retrieving the grid data in a WITH clause and the paging info is a local variable in LOAD.  The grid data changes based on changing user-selected filter values so the WITH is working as expected but the TOTAL records retrieved is always equal to the BATCH SIZE.  If I don't specify a page size then the page size defaults to 10 otherwise, it defaults to whatever I specify the page size to be.  I thought the batch size would determine the page size as we go through the pagination.  What am I missing?  I am using 19.4.

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