Access to First, Previous, Next, Last record on summary tab

When you want to open the first record, simply pass the operator as "=", start index as 1. Done. 
When you want to open the last record, pass the operator as "=", the startIndex as the total count from the query, or sort the data descending and pass the start index as 1. 

can you show it with some exmaple?

a!queryEntity(
  entity: cons!TT_TimesheetLog_Cons,
  query: a!query(
    pagingInfo: a!pagingInfo(
      startIndex: 1,
      batchSize: 1,
      sort: a!sortInfo(
        field: "id",
        ascending: if(
          or(ri!fetchingPrevious, ri!position = "LAST"),
          false(),
          true()
        )
      )
    ),
    filter: a!queryFilter(
      field: "id",
      operator: if(
        or(ri!position = "FIRST", ri!position = "LAST"),
        "=",
        if(ri!fetchingPrevious, "<", ">")
      ),
      value: ri!currentPrimaryKey
    )
  )
).data.id

it gives the current primary key in both situations of "First" and "Last" positions.

Oh. I missed one thing. Try now. 

a!queryEntity(
  entity: cons!TT_TimesheetLog_Cons,
  query: a!query(
    pagingInfo: a!pagingInfo(
      startIndex: 1,
      batchSize: 1,
      sort: a!sortInfo(
        field: "id",
        ascending: if(
          or(ri!fetchingPrevious, ri!position = "LAST"),
          false(),
          true()
        )
      )
    ),
    filter: a!queryFilter(
      field: "id",
      operator: if(ri!fetchingPrevious, "<", ">"),
      value: ri!currentPrimaryKey,
      applyWhen: a!isNullOrEmpty(ri!position)
    )
  )
).data.id

Oh. I missed one thing. Try now. 

a!queryEntity(
  entity: cons!TT_TimesheetLog_Cons,
  query: a!query(
    pagingInfo: a!pagingInfo(
      startIndex: 1,
      batchSize: 1,
      sort: a!sortInfo(
        field: "id",
        ascending: if(
          or(ri!fetchingPrevious, ri!position = "LAST"),
          false(),
          true()
        )
      )
    ),
    filter: a!queryFilter(
      field: "id",
      operator: if(ri!fetchingPrevious, "<", ">"),
      value: ri!currentPrimaryKey,
      applyWhen: a!isNullOrEmpty(ri!position)
    )
  )
).data.id

its working fine now.can you explain its logic please. from me i assume that its accessing the first index due to "start index" being given as 1 but how its accessing the "Last" index? is their "Last" a keyword for last index in appian? thanks

Nope. Once you retrieve the data in descending order, then the first record is basically the last record. If you look at the 10th row, there is a condition that if position="LAST" then we're fetching the data in descending order. 

Also, if it worked, please consider accepting the answer so other people can find the right answer if they are facing the same problem and other contributors do not invest their time in providing solutions.