static.faq.topic-browser.fetch-faq.html Maven / Gradle / Ivy
To perform a fetch operation, follow these steps:
-
Start by making the first fetch to populate the columns and headers lists.
These lists are used by filters and the column selector.
-
Each Fetch operation retrieves a specified number of records called the "Limit"
(the limit can be set in the 
input item).
If the topic has multiple partitions, KM automatically calculates the limit for each partition.
The sum of all partition limits equals the total limit you entered. The limits for each partition are distributed evenly.
For example, if the "Limit" is set to 100 and the topic has 16 partitions, each partition will have a limit of 6 records.
Therefore, after a fetch operation, KM will attempt to fetch 6 new records from each partition.
If a specific partition does not have 6 records, all the remaining records in that partition will be fetched,
resulting in a total number of records that is less than the "Limit".
-
Press the 
button to execute a forward fetch operation
starting from the "FIRST BATCH" position. The fetch operation continues until the size of the fetched result set equals
the limit or until the fetch reaches the end offset of a partition in some partitions.
In this case, the overall number of fetched records will be less than the limit.
-
There is a 
"Forward fetch button" available.
Pressing this button executes forward fetch operation starting from the "LAST BATCH" position.
The fetch operation continues until the size of the fetched result set equals the limit or until the fetch reaches the
end offset of a partition in some partitions.
In this case, the overall number of fetched records will be less than the limit.
This button is shown only if the "LAST BATCH" position is less than the "MAX" position for any partition.
-
There is also a 
"Backward fetch button" available.
Pressing this button executes a backward fetch operation starting from the "FIRST BATCH" position in the backward direction.
The fetch operation continues until the size of the fetched result set equals the limit or until the fetch reaches the start offset
of a partition in some partitions.
In this case, the number of totally fetched records will be less than the limit.
This button is shown only if the "MIN" position is less than the "FIRST BATCH" position for any partition.