# Production memory usage

**URL:** <https://forum.kx.com/t/production-memory-usage/9613>\
**Category:** Community Support\
**Tags:** kdb-and-q\
**Created:** [March 15, 2015, 7:19pm UTC](https://forum.kx.com/t/production-memory-usage/9613 "2015-03-15T19:19:00Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![abcfoots1](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@abcfoots1](https://forum.kx.com/u/abcfoots1)\
**Post date:** [March 15, 2015, 7:19pm UTC](https://forum.kx.com/t/production-memory-usage/9613/1 "2015-03-15T19:19:00Z")

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Given the following 2 scenarios:

1. A real time inmemory tick database generally not queried to frequently
2. A database of mostly static tables to which users can place unconstrained queries

what kind of max memory consumption does kx recommend for production usage? Should scenario 1 max out at ~50% physical memory before maybe requiring another database instance on another machine? Since scenario 2 could potentially result in extra memory being allocated from unconstrained queries would somewhere around 25-30% of physical memory be more reasonable? Or is there some general rule of thumb?

Thank you.

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<div class="post-metadata">

**Author:** ![LamHinYan](https://avatars.discourse-cdn.com/v4/letter/l/35a633/32.png) [@LamHinYan](https://forum.kx.com/u/LamHinYan)\
**Post date:** [March 16, 2015, 6:04am UTC](https://forum.kx.com/t/production-memory-usage/9613/2 "2015-03-16T06:04:00Z")

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Memory consumption and raw data capacity are different. Kdb 32 bit can report up to 4 GB memory usage. Windows task manager reports up to 2GB ram usage. My guess is half of the signed int/pointer range goes to negative numbers. Another half goes to garbage collection. That leaves 1 GB for raw data.

[http://kx.com/q/d/a/kdb+.htm#Limits](http://kx.com/q/d/a/kdb+.htm#Limits)

##### 22 Limits

Each database runs in memory and/or disk map-on-demand -- possibly partitioned. There is no limit on the size of a partitioned database but on 32-bit systems the main memory OLTP portion of a database is limited to about 1GB of raw data, i.e. 1/4 of the address space. The raw data of a main memory 64bit process should be limited to about 1/2 of available RAM.

/ memoryConsumptionTest.q

value each {"t", (string x), ": til 1024\*1024"} each til 231;

show .Q.w%(1024\*1024);

$ q memoryConsumptionTest.q

KDB+ 3.2 2015.02.10 Copyright (C) 1993-2015 Kx Systems

w32/ 4()core 4095MB yan yanicolaptop 192.168.30.219 NONEXPIRE

Welcome to kdb+ 32bit edition

For support please see [http://groups.google.com/d/forum/personal-kdbplus](http://groups.google.com/d/forum/personal-kdbplus)

Tutorials can be found at [Get started | Learn | kdb+ and q documentation - kdb+ and q documentation](http://code.kx.com/wiki/Tutorials)

To exit, type \

To remove this startup msg, edit q.q

used| 3696.113

heap| 3712

peak| 3712

wmax| 0

mmap| 0

mphy| 4096

syms| 0.0007648468

symw| 0.03010845

q)