.Q.gz - Not in Gzip format in java

kdb+

.Q.gz – Not in Gzip format in java

Posted by k-mambo on September 27, 2024 at 5:59 am

https://code.kx.com/q/ref/dotq/#gz-gzip

<pre class=”hljs language-q”>Unexpected exception thrown: java.util.zip.ZipException: Not in GZIP format

Is the compression result of .Q.gz different from the GZIP format?

code.kx.com
The .Q namespace – tools | Reference | kdb+ and q documentation - kdb+ and q documentation
The .Q namespace contains utility objects for q programming

rocuinneagain replied 1 day, 5 hours ago 3 Members · 2 Replies
2 Replies

pgyorok

Member
September 27, 2024 at 9:12 am
File compression | Database | kdb+ and q documentation – kdb+ and q documentation (kx.com)
- Use set and not gzip: they produce different results.
code.kx.com
File compression | Database | kdb+ and q documentation - kdb+ and q documentation
How to work with compressed files in kdb+

rocuinneagain

Member

September 27, 2024 at 10:36 am

The question is vague on what you are trying to do and how (no example code etc.)

Below is an example which when run results in:

HelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHelloHello

Java can decompress the data which kdb+ compressed with .Q.gz without issue:

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.zip.*;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.lang.String;
import com.kx.c;
public class Main {
    public static String decompress(final byte[] bytes) throws IOException {
        if (bytes == null || bytes.length == 0) {
            return "";
        }
        try (final GZIPInputStream ungzip = new GZIPInputStream(new ByteArrayInputStream(bytes))) {
            final ByteArrayOutputStream out = new ByteArrayOutputStream();
            final byte[] data = new byte[8192];
            int nRead;
            while ((nRead = ungzip.read(data)) != -1) {
                out.write(data, 0, nRead);
            }
            return out.toString();
        }
    }
    public static void main(String[] args) {
        c c = null;
        Object result = null;
        byte[] bytes = null;
        try {
            c = new c("localhost", 5001);
            String query="`byte$.Q.gz(9;400#\"Hello\")";
            result = c.k(query);
            bytes = ((byte[]) result);
            System.out.println(decompress(bytes));
        } catch (Exception e){
            System.err.println(e.toString());
        }
    }
}

This reply was modified 1 day, 4 hours ago by rocuinneagain.
This reply was modified 1 day, 4 hours ago by rocuinneagain.
This reply was modified 1 day, 4 hours ago by rocuinneagain.
This reply was modified 1 day, 4 hours ago by rocuinneagain.
This reply was modified 1 day, 4 hours ago by rocuinneagain.
This reply was modified 1 day, 4 hours ago by rocuinneagain.

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.Q.gz – Not in Gzip format in java

pgyorok

rocuinneagain