eatonphil

rnd_next(uchar* buf) for a storage engine sets up the current row of data. If there is data, it returns a 0. Otherwise it returns a HA_ERR_END_OF_FILE or other error.

Row data is written into the uchar* buf field. You might imagine you would return structured data for a row and the API would be like rnd_next(Fields**, field_count int). But that's not how the API works. You write the fields as bytes directly into uchar* buf.

The first X bytes are a NULL bitmap. One bit for each NULL-able column, padded out to a full byte. After that is each value for each field. For a table with two INT columns (they'd both be NULL-able), you'd write 9 bytes to uchar* buf. The first byte would be a NULL bitmap of all zeroes if both values in the row were not NULL. The next 4 bytes would be the first column's value. The last 4 bytes would be the second column's value.

Here's a diff for the BLACKHOLE engine, hardcoding a single row response: https://github.com/MariaDB/server/compare/11.4...eatonphil:mariadb:e0

eatonphil

The MySQL/MariaDB build process is complex, so it is easiest to build within the MySQL/MariaDB source tree. (I wasted basically a whole day trying to build a storage engine plugin outside the tree.)

Inside the MariaDB root, create a new directory, storage/memem.

$ mkdir storage/memem

The blackhole storage engine is the smallest existing one. So we'll copy from it and rename the minimum from it to get a new engine to compile and be usable from the server.

eatonphil

Assume that you've got MariaDB built and running locally. Let's say the install directory is in $MARIADB_LOCAL_INSTALL.

Enter the following into udf_minimal.c:

#include "mariadb.h"

my_bool mysum_init(UDF_INIT* initid, UDF_ARGS* args, char* message);
long long mysum(UDF_INIT* initid, UDF_ARGS* args, char* result,
              unsigned long* length, char* is_null, char* error);

eatonphil

Download and build.

$ git clone https://github.com/MariaDB/server.git mariadb
$ cd mariadb
$ mkdir build
$ cd build
$ cmake -DCMAKE_BUILD_TYPE=Debug ..
$ make -j8

eatonphil

struct BST<K: Ord + Clone, V: Ord + Clone> {
    key: Option<K>,
    value: Option<V>,
    left: Option<Box<BST<K, V>>>,
    right: Option<Box<BST<K, V>>>,
}

impl<K: Ord + Clone, V: Ord + Clone> BST<K, V> {
    fn init() -> Box<BST<K, V>> {
        return Box::new(BST::<K, V> {

eatonphil

default:
	gcc -O0 -g3 -Wall -Wextra -Wconversion -Wdouble-promotion \
		-Wno-unused-parameter -Wno-unused-function -Wno-sign-conversion \
		main.c

format:
	clang-format -i main.c

eatonphil

import math
import uuid


class BTree:
    def __init__(self, order=3):
        self.root = BTreeNode(order)

    def insert(self, toinsert):
        all_elements = self.list()

eatonphil

package main

import (
        "fmt"
        "time"
        "log"
        "os"
        "reflect"

        tb "github.com/tigerbeetledb/tigerbeetle-go"

eatonphil

./tigerbeetle start --addresses=3000 0_0.tigerbeetle | tee log
info(io): opening "0_0.tigerbeetle"...
info(main): 0: cluster=0: listening on 127.0.0.1:3000
info(message_bus): connection from client 227535350229908850722306115486582690844
thread 1684819 panic: reached unreachable code
/home/phil/tb/tigerbeetle/zig/lib/std/debug.zig:225:14: 0x269fcb in std.debug.assert (tigerbeetle)
    if (!ok) unreachable; // assertion failure
             ^
/home/phil/tb/tigerbeetle/src/lsm/manifest.zig:431:23: 0x43ef85 in lsm.manifest.ManifestType(lsm.table.TableType(u128,lsm.groove.IdTreeValue,lsm.groove.IdTreeValue.compare_keys,lsm.groove.IdTreeValue.key_from_value,554112867134706473364364839029663282043,lsm.groove.IdTreeValue.tombstone,lsm.groove.IdTreeValue.tombstone_from_key),storage.Storage).assert_level_table_counts (tigerbeetle)
                assert(manifest_level.table_count_visible <= table_count_visible_max);

eatonphil

const assert = require('node:assert/strict');

const { createClient } = require('tigerbeetle-node');

async function run() {
  const client = createClient({ cluster_id: 0, replica_addresses: ['3000'] });

  // Create two accounts
  let errors = await client.createAccounts([
    {