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Questions tagged [tombstone]

For questions about how the tombstone feature of a data-store or database works, or about how to implement such functionality.

A tombstone is a marker or flag used to indicate that a record has been deleted, as a substitute for actually deleting the record and immediately reclaiming the space it used. SQLServer, Microsoft Synchronization Services and Cassandra use tombstones.

Using tombstones can improve execution speed, at the cost of increased storage space.

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how to access android files /data/anr/traces.txt and /data/tombstones/tombstones

I am writing an application for reporting crashes and the relevant logs. So from my application I am trying to access traces.txt and tombstones, but I am getting an error: 03-25 09:48:46.220 W/System.err(10250): java.io.FileNotFoundException:…
learner
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What exactly happens when tombstone limit is reached

According to cassandra's log (see below) queries are getting aborted due to too many tombstones being present. This is happening because once a week I cleanup (delete) rows with a counter that is too low. This 'deletes' hundreds of thousands of rows…
natli
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Can I force cleanup of old tombstones?

I have recently lowered gc_grace_seconds for a CQL table. I am running LeveledCompactionStrategy. Is it possible for me to force purging of old tombstones from my SSTables?
Ztyx
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Overwrite row in cassandra with INSERT, will it cause tombstone?

Writing data to Cassandra without causing it to create tombstones are vital in our case, due to the amount of data and speed. Currently we have only written a row once, and then never had the need to update the row again, only fetch the data…
Andreas Mattisson
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Inserting null values into cassandra

I have some fields that I am storing into Cassandra, but some of them could be null at any given point. As there are quite a lot of them, it makes the code much more readable if I don’t check each one for null before adding it to the INSERT. Is…
ArchitGarg
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What does cassandra do during compaction?

I know that cassandra merges sstables, row-keys, remove tombstone and all. But i am really interested to know how it performs compaction ? As sstables are immutable does it copy all the relevant data to new file? and while writing to this new file…
samarth
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How to delete a large number of rows in Cassandra (and avoid potential tombstone issues)?

Oversimplifying the data model, we have the following tables: CREATE TABLE storage ( id timeuuid, foo blob, bar blob, baz blob, data blob, PRIMARY KEY ((id)) ); CREATE TABLE storage_idx_by_foo ( foo blob, id…
Miloš Ranđelović
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Cassandra and Tombstones: Creating a Row , Deleting the Row, Recreating the Row = Performance?

Could someone please explain, what effect the following process has on tombstones: 1.)Creating a "Row" with Key "1" ("Fields": user, password, date) 2.)Deleting the "Row" with Key "1" 3.)Creating a "Row" with Key "1" ("Fields": user,…
Markus
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Cassandra Tombstoning warning and failure thresholds breached

We are running a Titan Graph DB server backed by Cassandra as a persistent store and are running into an issue with reaching the limit on Cassandra tombstone thresholds that is causing our queries to fail / timeout periodically as data accumulates.…
Rohit
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Is there any way to have Cassandra safely remove tombstones *before* gc_grace_seconds have elapsed?

I know early removal of tombstones is dangerous because it can cause deleted data to be resurrected, but if all replicas have confirmed deletion then such removal should be safe. For example, if a table has replication factor 3 and all 3 nodes…
jonderry
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how does tombstones works in android-kernel

mkdir /data/tombstones 0771 system system symlink /data/tombstones /tombstones mkdir /tombstones/mdm 0771 system system mkdir /tombstones/modem 0771 system system mkdir /tombstones/lpass 0771 system system # For firmwares …
Ravike14
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Cassandra lookup query is quite slow after deleting large bundle of data

Currently, I have a cassandra column family with large rows of data, to say more than 100,000. Now, I'd like to remove all data in this column family and the problem came up: After all data is removed, I execute a lookup query in this column family,…
Fify
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What types of tombstones does Cassandra support?

What types of tombstones does Cassandra (version 2) support? According to this article it supports (in CQL terms): a specific column for a row. static columns. all rows for a partition key. Have I missed any other types of tombstones? Removing a…
Ztyx
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How to define a C++ iterator that skips tombstones

I am implementing a container that presents a map-like interface. The physicals implementation is an std::vector>. A K object remembers its assigned position in the vector. It is possible for a K object to get destroyed. In that…
John Yates
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Avoid zombie data in cassandra

Recently I faced an issue in a customer setup with a 3 node cluster, where one node went down and came online only after 12 days. The default gc_grace_seconds for most of the table has been set to 1 day in our scenario and there are a lot of…
Vishal
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