Allow to scan keys with the suffix #2222

baobaomaomeng · 2024-04-04T16:22:02Z

After modifying the code, I'm encountering some strange issues. I don't understand why this test is failing.

At the same time, there's a bit of a performance issue. I'm not sure about the optimal number of scans for substring matching and suffix matching, I haven't set a limit yet. In the next couple of days, I'll try to add support for HSCAN, SSCAN, and ZSCAN.

jihuayu · 2024-04-05T01:10:23Z

@baobaomaomeng You can add a config to set the optimal number. We can talk about the default value later.
If this test case doesn't your need, you can hide it in your local.
You can use ./x.py check format to format the code.

baobaomaomeng · 2024-04-14T15:13:22Z

@baobaomaomeng You can add a config to set the optimal number. We can talk about the default value later. If this test case doesn't your need, you can hide it in your local. You can use ./x.py check format to format the code.

I've now added some tests,add support hsacn zscan and SSCAN, and the final step is to add configuration options. I'm not sure how to add configuration options, nor do I know what a good default number of search times would be. I feel like I need some help in this area.

jihuayu · 2024-04-14T23:53:45Z

@baobaomaomeng That's great, thank you for your efforts.

Regarding how to add configuration items, you can refer to this PR.

The default number may be any number(such as 100,000). We can have the Reviewers confirm the final value, this modification is quite simple.

baobaomaomeng · 2024-04-16T16:13:27Z

@baobaomaomeng That's great, thank you for your efforts.

Regarding how to add configuration items, you can refer to this PR.

The default number may be any number(such as 100,000). We can have the Reviewers confirm the final value, this modification is quite simple.

One point that confuses me is why the limit in the scan operator is not a configuration item, and now I need to add the maximum number to scan at once into the configuration items.

jihuayu · 2024-04-24T08:36:11Z

@baobaomaomeng Hi, can you resolve the conflicts?

jihuayu

Good work! Thank you for your contribution.
Can you please resolve the code conflicts first? I will continue to review the code after resolving the conflicts.

jihuayu · 2024-04-24T08:39:53Z

src/commands/scan_base.h

@@ -83,6 +89,7 @@ class CommandScanBase : public Commander {
  std::string cursor_;
  std::string prefix_;
  int limit_ = 20;
+  int pm_ = 0;


Can you use enum instead of it?
Can you change and rename it to prefix_mode_?

jihuayu · 2024-04-24T08:50:53Z

src/commands/cmd_server.cc

@@ -878,7 +878,7 @@ class CommandScan : public CommandScanBase {

    std::vector<std::string> keys;
    std::string end_key;
-    auto s = redis_db.Scan(key_name, limit_, prefix_, &keys, &end_key);
+    auto s = redis_db.Scan(key_name, limit_, srv->GetConfig()->max_scan_num, prefix_, &keys, &end_key, pm_);


This code looks ugly. Can we have some good way to deal with config?

I have no clue about this, do you have any suggestions?

jihuayu · 2024-04-24T08:59:20Z

src/storage/redis_db.cc

+      if (cnt_false >= scan_false_limit) {
+        break;
+      }


Why not put those codes to begin?

if (!scan_match_check()) { cnt_false++; if (cnt_false < scan_false_limit) { continue; } else { break; } }

jihuayu · 2024-04-24T09:05:53Z

src/storage/redis_db.cc

+      if (keys->empty() && cnt_false >= scan_false_limit) {
        end_cursor->append(user_key);
      }


There may be a situation where some keys have been found, but cnt_false >= scan_false_limit.

jihuayu · 2024-04-24T09:13:04Z

src/storage/redis_db.cc

+rocksdb::Status Database::Scan(const std::string &cursor, uint64_t scan_success_limit, uint64_t scan_false_limit,
+                               const std::string &fix, std::vector<std::string> *keys, std::string *end_cursor,
+                               const int pm) {


Can you change the param fix to a more meaningful name? Can you keep the name the same as the header file?

PragmaTwice · 2024-05-04T06:25:22Z

.gitignore

@@ -40,9 +40,13 @@ version.h
 .idea
 .vscode
 .cache
+.gitignore


why it's ignored?

I'm sorry, that was my oversight.

PragmaTwice · 2024-05-04T06:25:35Z

.gitignore

+test
 testdb

 build
 cmake-build-*
+debug-build
+test


duplicated test

PragmaTwice · 2024-05-04T06:26:28Z

tests/gocase/unit/scan/scan_test.go

@@ -187,7 +187,27 @@ func ScanTest(t *testing.T, rdb *redis.Client, ctx context.Context) {
 		require.Equal(t, []string{"1", "10", "foo", "foobar"}, keys)
 	})

-	t.Run("ZSCAN with PATTERN", func(t *testing.T) {
+	t.Run("HSCAN with subkey PATTERN", func(t *testing.T) {


seems we need more test cases

PragmaTwice · 2024-05-04T06:27:32Z

src/commands/scan_base.h

@@ -39,14 +41,20 @@ class CommandScanBase : public Commander {

    return ParseAdditionalFlags<true>(parser);
  }
-


please don't introduce random changes.

git-hulk · 2024-05-04T06:14:15Z

.gitignore

 testdb

 build
 cmake-build-*
+debug-build
+test


duplicate line, it has been added in previous section.

git-hulk · 2024-05-04T06:21:52Z

src/config/config.cc

@@ -152,6 +153,7 @@ Config::Config() {
      {"pidfile", true, new StringField(&pidfile, kDefaultPidfile)},
      {"max-io-mb", false, new IntField(&max_io_mb, 0, 0, INT_MAX)},
      {"max-bitmap-to-string-mb", false, new IntField(&max_bitmap_to_string_mb, 16, 0, INT_MAX)},
+      {"max-scan-num", false, new IntField(&max_scan_num, 2, 0, INT_MAX)},


Seems 2 is too smaller to be as the max_scan_num?

it's just for test easy，jihuayu say they will determine the final value.

git-hulk · 2024-05-04T06:25:00Z

src/storage/redis_db.cc

@@ -309,10 +314,12 @@ rocksdb::Status Database::Keys(const std::string &prefix, std::vector<std::strin
  return rocksdb::Status::OK();
 }

-rocksdb::Status Database::Scan(const std::string &cursor, uint64_t limit, const std::string &prefix,
-                               std::vector<std::string> *keys, std::string *end_cursor, RedisType type) {
+rocksdb::Status Database::Scan(const std::string &cursor, uint64_t scan_success_limit, uint64_t scan_false_limit,


scan_matched_limt and scan_mismatched_limit should be a better name in this scenario.

The parameter of the SCAN command is too long now, it's time to group the scan parameters into a struct.

PragmaTwice · 2024-05-04T06:36:52Z

src/storage/redis_db.cc

+rocksdb::Status Database::Scan(const std::string &cursor, uint64_t scan_success_limit, uint64_t scan_false_limit,
+                               const std::string &match_str, std::vector<std::string> *keys, std::string *end_cursor,
+                               RedisType type, const MatchType match_mode) {


I have some questions about your design.

But before that, could you give a little introduction about your general design and supported patterns in the PR description?

Then we can have a detailed review on your code.

Refer to Redis glob-style patterns:

Supported glob-style patterns:

h?llo matches hello, hallo and hxllo
h*llo matches hllo and heeeello
h[ae]llo matches hello and hallo, but not hillo
h[^e]llo matches hallo, hbllo, ... but not hello
h[a-b]llo matches hallo and hbllo

I just added two matching patterns.
such as
*llo matches ello,hello,eeeello
l matches l,ll,llo,ello,hello

And，i add scan_false_time limit to config,beacasue if we use suffix,substring match, we need scan one by one, and the potentially long time may be unacceptable. so I add this argument in scan,zsan,sscan,hscan command。I found that the three scan methods to get the last scanned key are all different, which is not convenient for me to modify，so i add a string value in CommandSubkeyScanBase to represented the last key that was scanned。

I've been thinking about how to design a scalable scan, but I don't have any ideas. This might be a bit difficult for me. I think I need some guidance on the thought process right now.

PragmaTwice · 2024-05-04T06:41:02Z

In my opinion, we need a well-designed solution for implementing Redis glob-style patterns that is scalable, rather than just handling specific cases. If the design is not scalable, we may have to remove all modifications when aiming to support the complete pattern cases.

baobaomaomeng · 2024-05-04T08:59:19Z

In my opinion, we need a well-designed solution for implementing Redis glob-style patterns that is scalable, rather than just handling specific cases. If the design is not scalable, we may have to remove all modifications when aiming to support the complete pattern cases.

Thank you for your review, but this is not consistent with the goal I communicated at the beginning. I now need to rewrite my code, and I think I need to consider how to write it.Could you give me some reference suggestions？

PragmaTwice · 2024-10-29T09:55:56Z

closed by #2608.

baobaomaomeng force-pushed the unstable branch from f8d7f35 to 5aa86c6 Compare April 14, 2024 15:09

baobaomaomeng marked this pull request as ready for review April 23, 2024 15:56

jihuayu reviewed Apr 24, 2024

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baobaomaomeng force-pushed the unstable branch from 4a712de to 2c8a4ff Compare April 25, 2024 16:03

baobaomaomeng force-pushed the unstable branch 2 times, most recently from 98cff58 to 65a8cd5 Compare May 4, 2024 05:56

git-hulk changed the title ~~add scan substring,suffix~~ Allow to scan keys with the suffix May 4, 2024

git-hulk requested review from jihuayu and git-hulk May 4, 2024 06:12

PragmaTwice reviewed May 4, 2024

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.gitignore Outdated

Comment on lines 46 to 52

test

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build

cmake-build-*

debug-build

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duplicated test

PragmaTwice reviewed May 4, 2024

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git-hulk reviewed May 4, 2024

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PragmaTwice reviewed May 4, 2024

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add scan substring,suffix

7aaf96d

baobaomaomeng force-pushed the unstable branch from 65a8cd5 to c3c1c12 Compare May 27, 2024 15:50

add scan_false_limit in all scan

b714528

baobaomaomeng force-pushed the unstable branch from c3c1c12 to b714528 Compare May 29, 2024 06:19

PragmaTwice closed this Oct 29, 2024

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Allow to scan keys with the suffix #2222

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PragmaTwice commented Oct 29, 2024

		@@ -39,14 +41,20 @@ class CommandScanBase : public Commander {

		return ParseAdditionalFlags<true>(parser);
		}

Allow to scan keys with the suffix #2222

Allow to scan keys with the suffix #2222

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baobaomaomeng commented Apr 4, 2024

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PragmaTwice commented May 4, 2024

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PragmaTwice commented Oct 29, 2024