How to find out fragmented indexes and defragment them in PostgreSQL?
来源： https://stackoverflow.com/questions/52444912/how-to-find-out-fragmented-indexes-and-defragment-them-in-postgresql
defragmentation
What is a good algorithm for compacting records in a blocked file?
问题 Suppose you have a large file made up of a bunch of fixed size blocks. Each of these blocks contains some number of variable sized records. Each record must fit completely within a single block and then such records by definition are never larger than a full block. Over time, records are added to and deleted from these blocks as records come and go from this "database". At some point, especially after perhaps many records are added to the database and several are removed - many of the blocks
Reconstructing data from PCAP sniff
问题 I am trying to sniff HTTP data through libpcap and get all the http contents (header+payload) after processing the TCP payload. As per my discussion at Writing an http sniffer (or any other application level sniffer) , I am facing problems due to fragmentation - I need to reconstruct the whole stream (or defragment it) to get a complete HTTP packet, and this is where I need some help. Thanks in anticipation !! 回答1: It's really pretty simple. Just take the ethernet frames that you get from
Disk Defrag and Disk Clean up using Python Script
问题 Can you help me on how to make this script work. For Defrag import os; defragmentation=os.popen('defrag.exe /C').read() print(defragmentation); For Disk Clean up import os; clean=os.popen('cleanmgr.exe /sagerun:1').read() print(clean); Upon trying this scripts, it didnt do anything and no error message prompt. Thank you. 回答1: If your defrag.exe or cleanmgr.exe are not in your path , they won't execute and you won't get an error message You would need to run the scripts as an administrator to
does Firebird defrag? If so, like a clustered index?
问题 I've seen a few (literally, only a few) links and nothing in the documentation that talks about clustering with Firebird, that it can be done. Then, I shot for the moon on this question CLUSTER command for Firebird?, but answerer told me that Firebird doesn't even have clustered indexes at all, so now I'm really confused. Does Firebird physically order data at all? If so, can it be ordered by any key, not just primary, and can the clustering/defragging be turned on and off so that it only
Can I optimize a Mercurial clone?
问题 My Mercurial clone has become incredibly slow, presumably due to on-disk fragmentation. Is there a way to optimize it? The obvious way it to make a new clone, then copy my MQ, saved bundles, hgrc, etc, to the new clone and delete the old one. But it seems like someone might have run into this problem before and made an extension to do it? 回答1: If the manifest gets particularly large then it can result in slow performance. Mercurial has an alternative repository format - generaldelta - that
IP Fragmentation and Reassembly
问题 I am currently going through my networking slides and was wondering if someone could help me with the concept of fragmentation and reassembly. I understand how it works, namely how datagrams are split into smaller chunks because network links have a MTU. However the example in the picture is confusing me. So the first two sections show a length of 1500, because this is the MSU, but shouldn't this mean that the last one should have 1000 (for a total of 4000 bytes) and not 1040? Where did these
IP Fragmentation and Reassembly
I am currently going through my networking slides and was wondering if someone could help me with the concept of fragmentation and reassembly. I understand how it works, namely how datagrams are split into smaller chunks because network links have a MTU. However the example in the picture is confusing me. So the first two sections show a length of 1500, because this is the MSU, but shouldn't this mean that the last one should have 1000 (for a total of 4000 bytes) and not 1040? Where did these extra 40 bytes come from? My guess is that because the previous two fragments both had a header of 20
What is a good algorithm for compacting records in a blocked file?
Suppose you have a large file made up of a bunch of fixed size blocks. Each of these blocks contains some number of variable sized records. Each record must fit completely within a single block and then such records by definition are never larger than a full block. Over time, records are added to and deleted from these blocks as records come and go from this "database". At some point, especially after perhaps many records are added to the database and several are removed - many of the blocks may end up only partially filled. What is a good algorithm to shuffle the records around in this
Can I optimize a Mercurial clone?
My Mercurial clone has become incredibly slow, presumably due to on-disk fragmentation. Is there a way to optimize it? The obvious way it to make a new clone, then copy my MQ, saved bundles, hgrc, etc, to the new clone and delete the old one. But it seems like someone might have run into this problem before and made an extension to do it? If the manifest gets particularly large then it can result in slow performance. Mercurial has an alternative repository format - generaldelta - that can often result in much smaller manifests. You can check the size of your manifest using: ls -lh .hg/store/