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[BP-7.2.5]- Investigate avg_page_size < avg_item_size

Description

During a CBSE investigation, on one of the unaffected nodes (node1), I come across stats for an instance where there were periods during which avg_page_size < avg_item_size. Below are the two successive time intervals. There were no change in inserts, items_count and total_records, no splits, no merges. (There was increase in compacts count, but that does not necessarily mean page was compacted).  

Instance :indexstorage_iWatchXCustomerJourney:Idx_caseId_hitDisp_IWXCJICR_v2:11515755198712134866:1  

2023-06-11T22:35:18.747+00:00 

             "act_max_delta_len": 2,
             "act_max_page_items": 4,
             "act_min_page_items": 1,
             "allocated": 23229781419,
             "allocated_index": 539036705,
             "avg_item_size": 3068,
             "avg_page_size": 4522,

             "page_bytes": 5933678,
             "page_bytes_compressed": 1450977430,
             "page_bytes_marshalled": 13390062693,
             "page_cnt": 1312,
             "page_itemcnt": 1934,

2023-06-11T22:52:19.086+00:00

            "act_max_delta_len": 2,
            "act_max_page_items": 4,
            "act_min_page_items": 1,
            "avg_item_size": 10057,
            "avg_page_size": 4971,             

            "page_bytes": 4747328,
            "page_bytes_compressed": 1452011158,
            "page_bytes_marshalled": 13399840267,
            "page_cnt": 955,
            "page_itemcnt": 472,

I looked at computePageStats2 and addPageStats which seemed ok. With respect to work context trimming, we are merging the related stats which seemed ok. The stats are then sampled in (s *Plasma) computePageStats(). Need to investigate this more.

Detailed Stats :

2023-06-11T22:35:18.747+00:00 

indexstorage_iWatchXCustomerJourney:Idx_caseId_hitDisp_IWXCJICR_v2:11515755198712134866:1 

2023-06-11T22:52:19.086+00:00 indexstorage_iWatchXCustomerJourney:Idx_caseId_hitDisp_IWXCJICR_v2:11515755198712134866:1

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Link to Log File, atop/blg, CBCollectInfo, Core dump

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Release Notes Description

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is a backport of

Activity

Beth Favini August 12, 2024 at 11:21 AM

We are working on release notes for Server 7.2.6. If this issue should be included in the release notes, please do the following:

Add the releasenote label
Include a brief description of the issue and resolution (from the customer's point of view).
Thank you

Beth Favini June 6, 2024 at 8:26 PM

We are preparing the 7.2.6 release notes. If this fix is customer-facing, please add the releasenote label to the issue so it will be picked up by our filter.

Beth Favini June 3, 2024 at 5:46 PM

We are preparing the 7.2.5 release notes. If this fix is customer-facing, please add the releasenote label to the issue so it will be picked up by our filter.

CB robot April 18, 2024 at 11:47 PM

Build couchbase-server-7.2.6-8004 contains plasma commit 2b8dba7 with commit message:
[BP]: Count items from compressDelta in computePageStats2

CB robot April 18, 2024 at 11:44 PM

Build couchbase-server-7.2.5-7596 contains plasma commit 2b8dba7 with commit message:
[BP]: Count items from compressDelta in computePageStats2

Fixed
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Instabug

Open Instabug

PagerDuty

Sentry

Zendesk Support

Created April 16, 2024 at 9:20 PM
Updated October 21, 2024 at 11:20 PM
Resolved April 19, 2024 at 12:08 AM
Instabug