Skip to content

Fix GEOHASH last character: always output '0' for Redis compatibility #1635

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Copilot wants to merge 5 commits into
base: main
Choose a base branch
from
+18 −13
Open

Fix GEOHASH last character: always output '0' for Redis compatibility #1635

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
1545037
Initial plan
Copilot Mar 17, 2026
4c55847
Fix GEOHASH last character to always return '0' for Redis compatibility
Copilot Mar 17, 2026
f52707b
Revert global.json SDK version change
Copilot Apr 1, 2026
e7af1d5
Merge branch 'main' into copilot/fix-geohash-last-character
badrishc Apr 7, 2026
040fc19
Refactor GetGeoHashCode per PaulusParssinen's suggestion
Copilot Apr 7, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion global.json
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
{
"sdk": {
"version": "10.0.103",
"version": "10.0.102",
"rollForward": "latestMajor",
"allowPrerelease": false
}
Expand Down
9 changes: 7 additions & 2 deletions libs/server/Objects/SortedSetGeo/GeoHash.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -239,8 +239,13 @@ public static string GetGeoHashCode(long hash)

for (var i = 0; i < chars.Length; i++)
{
// Shift and mask the five most significant bits for index to the base-32 table.
chars[i] = (char)base32Chars[(int)(hash >> (BitsOfPrecision - 5)) & 0x1F];
// We have just 52 bits, but the API outputs an 11-character geohash (55 bits).
// For compatibility with Redis, the last character is always '0' since the
// remaining bits are not stored with sufficient precision to determine it.
var idx = i < chars.Length - 1
? (int)(hash >> (BitsOfPrecision - 5)) & 0x1F
Copy link
Copy Markdown
Contributor

@PaulusParssinen PaulusParssinen Mar 17, 2026 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Consider instead something along the lines of

var base32Chars = "0123456789bcdefghjkmnpqrstuvwxyz"u8;

// We have just 52 bits, but the API outputs an 11-character geohash (55 bits).
// For compatibility with Redis, the last character is always '0'.
chars[^1] = '0';

for (var i = 0; i < chars.Length - 1; i++)
{
    // Shift and mask the five most significant bits for index to the base-32 table.
    chars[i] = (char)base32Chars[(int)(hash >> (BitsOfPrecision - 5)) & 0x1F];

    // Shift the encoded bits out.
    hash <<= 5;
}

Copy link
Copy Markdown
Collaborator

@badrishc badrishc Apr 1, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@copilot - incorporate this feedback

: 0;
chars[i] = (char)base32Chars[idx];

// Shift the encoded bits out.
hash <<= 5;
Expand Down
17 changes: 9 additions & 8 deletions test/Garnet.test/GeoHashTests.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -42,15 +42,15 @@ public void CanEncodeAndDecodeCoordinates(double latitude, double longitude)
}

[Test]
[TestCase(30.5388942218, 104.0555758833, 4024744861876082, "wm3vxz6vywh")]
[TestCase(27.988056, 86.925278, 3636631039000829, "tuvz4p141z8")]
[TestCase(30.5388942218, 104.0555758833, 4024744861876082, "wm3vxz6vyw0")]
[TestCase(27.988056, 86.925278, 3636631039000829, "tuvz4p141z0")]
[TestCase(37.502669, 15.087269, 3476216502357864, "sqdtr74hyu0")]
[TestCase(38.115556, 13.361389, 3476004292229755, "sqc8b49rnys")]
[TestCase(38.918250, -77.427944, 1787100258949719, "dqbvqhfenps")]
[TestCase(38.115556, 13.361389, 3476004292229755, "sqc8b49rny0")]
[TestCase(38.918250, -77.427944, 1787100258949719, "dqbvqhfenp0")]
[TestCase(0.0, 0.0, 0xC000000000000, "s0000000000")]
[TestCase(-90.0, -180.0, 0, "00000000000")]
[TestCase(90.0, 180.0, 0xFFFFFFFFFFFFF, "zzzzzzzzzzs")]
[TestCase(89.99999999999999, 179.99999999999997, 0xFFFFFFFFFFFFF, "zzzzzzzzzzs")]
[TestCase(90.0, 180.0, 0xFFFFFFFFFFFFF, "zzzzzzzzzz0")]
[TestCase(89.99999999999999, 179.99999999999997, 0xFFFFFFFFFFFFF, "zzzzzzzzzz0")]
public void CanEncodeAndDecodeCoordinatesWithGeoHashCode(
double latitude,
double longitude,
Expand All @@ -62,8 +62,9 @@ public void CanEncodeAndDecodeCoordinatesWithGeoHashCode(

ClassicAssert.AreEqual(expectedHashInteger, hashInteger);

// Note: while we are comparing the entire textual representation of geohash (11 characters)
// we are comparing in 52-bit precision, not 55-bit that is expected from GeoHash standard.
// Note: while we are comparing the entire textual representation of geohash (11 characters),
// the data is stored in 52-bit precision (not 55-bit as required by the GeoHash standard).
// For compatibility with Redis, the last character is always '0'.
ClassicAssert.AreEqual(expectedHash, hash);
}
}
Expand Down
8 changes: 4 additions & 4 deletions test/Garnet.test/RespSortedSetGeoTests.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -221,7 +221,7 @@ public void CanUseGeoPos()

var responseHash = db.GeoHash(new RedisKey("SecondKey"), ["Palermo"]);
ClassicAssert.AreEqual(1, responseHash.Length);
ClassicAssert.AreEqual("sqc8b49rnys", responseHash[0]);
ClassicAssert.AreEqual("sqc8b49rny0", responseHash[0]);

memresponse = db.Execute("MEMORY", "USAGE", "SecondKey");
actualValue = ResultType.Integer == memresponse.Resp2Type ? Int32.Parse(memresponse.ToString()) : -1;
Expand Down Expand Up @@ -590,16 +590,16 @@ public void CanUseGeoHash(int bytesSent)
var response = lightClientRequest.Execute("GEOADD Sicily 13.361389 38.115556 Palermo 15.087269 37.502669 Catania", "PING", expectedResponse.Length, bytesSent);
ClassicAssert.AreEqual(expectedResponse, response);

expectedResponse = "*3\r\n$11\r\nsqc8b49rnys\r\n$11\r\nsqdtr74hyu0\r\n$-1\r\n+PONG\r\n";
expectedResponse = "*3\r\n$11\r\nsqc8b49rny0\r\n$11\r\nsqdtr74hyu0\r\n$-1\r\n+PONG\r\n";
response = lightClientRequest.Execute("GEOHASH Sicily Palermo Catania Unknown", "PING", expectedResponse.Length, bytesSent);
ClassicAssert.AreEqual(expectedResponse, response);

expectedResponse = "*3\r\n$11\r\nsqc8b49rnys\r\n$11\r\nsqdtr74hyu0\r\n$-1\r\n";
expectedResponse = "*3\r\n$11\r\nsqc8b49rny0\r\n$11\r\nsqdtr74hyu0\r\n$-1\r\n";
response = lightClientRequest.Execute("GEOHASH Sicily Palermo Catania Unknown", expectedResponse.Length, bytesSent);
ClassicAssert.AreEqual(expectedResponse, response);

// Execute command in chunks
expectedResponse = "*1\r\n$11\r\nsqc8b49rnys\r\n";
expectedResponse = "*1\r\n$11\r\nsqc8b49rny0\r\n";
response = lightClientRequest.Execute("GEOHASH Sicily Palermo", expectedResponse.Length, bytesSent);
ClassicAssert.AreEqual(expectedResponse, response);
}
Expand Down
Loading