Line data Source code
1 : //! See docs/rfcs/031-sharding-static.md for an overview of sharding.
2 : //!
3 : //! This module contains a variety of types used to represent the concept of sharding
4 : //! a Neon tenant across multiple physical shards. Since there are quite a few of these,
5 : //! we provide an summary here.
6 : //!
7 : //! Types used to describe shards:
8 : //! - [`ShardCount`] describes how many shards make up a tenant, plus the magic `unsharded` value
9 : //! which identifies a tenant which is not shard-aware. This means its storage paths do not include
10 : //! a shard suffix.
11 : //! - [`ShardNumber`] is simply the zero-based index of a shard within a tenant.
12 : //! - [`ShardIndex`] is the 2-tuple of `ShardCount` and `ShardNumber`, it's just like a `TenantShardId`
13 : //! without the tenant ID. This is useful for things that are implicitly scoped to a particular
14 : //! tenant, such as layer files.
15 : //! - [`ShardIdentity`]` is the full description of a particular shard's parameters, in sufficient
16 : //! detail to convert a [`Key`] to a [`ShardNumber`] when deciding where to write/read.
17 : //! - The [`ShardSlug`] is a terse formatter for ShardCount and ShardNumber, written as
18 : //! four hex digits. An unsharded tenant is `0000`.
19 : //! - [`TenantShardId`] is the unique ID of a particular shard within a particular tenant
20 : //!
21 : //! Types used to describe the parameters for data distribution in a sharded tenant:
22 : //! - [`ShardStripeSize`] controls how long contiguous runs of [`Key`]s (stripes) are when distributed across
23 : //! multiple shards. Its value is given in 8kiB pages.
24 : //! - [`ShardLayout`] describes the data distribution scheme, and at time of writing is
25 : //! always zero: this is provided for future upgrades that might introduce different
26 : //! data distribution schemes.
27 : //!
28 : //! Examples:
29 : //! - A legacy unsharded tenant has one shard with ShardCount(0), ShardNumber(0), and its slug is 0000
30 : //! - A single sharded tenant has one shard with ShardCount(1), ShardNumber(0), and its slug is 0001
31 : //! - In a tenant with 4 shards, each shard has ShardCount(N), ShardNumber(i) where i in 0..N-1 (inclusive),
32 : //! and their slugs are 0004, 0104, 0204, and 0304.
33 :
34 : use std::hash::{Hash, Hasher};
35 :
36 : #[doc(inline)]
37 : pub use ::utils::shard::*;
38 : use postgres_ffi::relfile_utils::INIT_FORKNUM;
39 : use serde::{Deserialize, Serialize};
40 :
41 : use crate::key::Key;
42 : use crate::models::ShardParameters;
43 :
44 : /// The ShardIdentity contains enough information to map a [`Key`] to a [`ShardNumber`],
45 : /// and to check whether that [`ShardNumber`] is the same as the current shard.
46 0 : #[derive(Clone, Copy, Serialize, Deserialize, Eq, PartialEq, Debug)]
47 : pub struct ShardIdentity {
48 : pub number: ShardNumber,
49 : pub count: ShardCount,
50 : pub stripe_size: ShardStripeSize,
51 : layout: ShardLayout,
52 : }
53 :
54 : /// Hash implementation
55 : ///
56 : /// The stripe size cannot change dynamically, so it can be ignored for efficiency reasons.
57 : impl Hash for ShardIdentity {
58 585702 : fn hash<H: Hasher>(&self, state: &mut H) {
59 585702 : let ShardIdentity {
60 585702 : number,
61 585702 : count,
62 585702 : stripe_size: _,
63 585702 : layout: _,
64 585702 : } = self;
65 585702 :
66 585702 : number.0.hash(state);
67 585702 : count.0.hash(state);
68 585702 : }
69 : }
70 :
71 : /// Stripe size in number of pages
72 0 : #[derive(Clone, Copy, Serialize, Deserialize, Eq, PartialEq, Debug)]
73 : pub struct ShardStripeSize(pub u32);
74 :
75 : impl Default for ShardStripeSize {
76 13 : fn default() -> Self {
77 13 : DEFAULT_STRIPE_SIZE
78 13 : }
79 : }
80 :
81 : /// Layout version: for future upgrades where we might change how the key->shard mapping works
82 0 : #[derive(Clone, Copy, Serialize, Deserialize, Eq, PartialEq, Hash, Debug)]
83 : pub struct ShardLayout(u8);
84 :
85 : const LAYOUT_V1: ShardLayout = ShardLayout(1);
86 : /// ShardIdentity uses a magic layout value to indicate if it is unusable
87 : const LAYOUT_BROKEN: ShardLayout = ShardLayout(255);
88 :
89 : /// Default stripe size in pages: 256MiB divided by 8kiB page size.
90 : const DEFAULT_STRIPE_SIZE: ShardStripeSize = ShardStripeSize(256 * 1024 / 8);
91 :
92 : #[derive(thiserror::Error, Debug, PartialEq, Eq)]
93 : pub enum ShardConfigError {
94 : #[error("Invalid shard count")]
95 : InvalidCount,
96 : #[error("Invalid shard number")]
97 : InvalidNumber,
98 : #[error("Invalid stripe size")]
99 : InvalidStripeSize,
100 : }
101 :
102 : impl ShardIdentity {
103 : /// An identity with number=0 count=0 is a "none" identity, which represents legacy
104 : /// tenants. Modern single-shard tenants should not use this: they should
105 : /// have number=0 count=1.
106 1447 : pub const fn unsharded() -> Self {
107 1447 : Self {
108 1447 : number: ShardNumber(0),
109 1447 : count: ShardCount(0),
110 1447 : layout: LAYOUT_V1,
111 1447 : stripe_size: DEFAULT_STRIPE_SIZE,
112 1447 : }
113 1447 : }
114 :
115 : /// An unsharded identity with the given stripe size (if non-zero). This is typically used to
116 : /// carry over a stripe size for an unsharded tenant from persistent storage.
117 0 : pub fn unsharded_with_stripe_size(stripe_size: ShardStripeSize) -> Self {
118 0 : let mut shard_identity = Self::unsharded();
119 0 : if stripe_size.0 > 0 {
120 0 : shard_identity.stripe_size = stripe_size;
121 0 : }
122 0 : shard_identity
123 0 : }
124 :
125 : /// A broken instance of this type is only used for `TenantState::Broken` tenants,
126 : /// which are constructed in code paths that don't have access to proper configuration.
127 : ///
128 : /// A ShardIdentity in this state may not be used for anything, and should not be persisted.
129 : /// Enforcement is via assertions, to avoid making our interface fallible for this
130 : /// edge case: it is the Tenant's responsibility to avoid trying to do any I/O when in a broken
131 : /// state, and by extension to avoid trying to do any page->shard resolution.
132 0 : pub fn broken(number: ShardNumber, count: ShardCount) -> Self {
133 0 : Self {
134 0 : number,
135 0 : count,
136 0 : layout: LAYOUT_BROKEN,
137 0 : stripe_size: DEFAULT_STRIPE_SIZE,
138 0 : }
139 0 : }
140 :
141 : /// The "unsharded" value is distinct from simply having a single shard: it represents
142 : /// a tenant which is not shard-aware at all, and whose storage paths will not include
143 : /// a shard suffix.
144 0 : pub fn is_unsharded(&self) -> bool {
145 0 : self.number == ShardNumber(0) && self.count == ShardCount(0)
146 0 : }
147 :
148 : /// Count must be nonzero, and number must be < count. To construct
149 : /// the legacy case (count==0), use Self::unsharded instead.
150 13369 : pub fn new(
151 13369 : number: ShardNumber,
152 13369 : count: ShardCount,
153 13369 : stripe_size: ShardStripeSize,
154 13369 : ) -> Result<Self, ShardConfigError> {
155 13369 : if count.0 == 0 {
156 1 : Err(ShardConfigError::InvalidCount)
157 13368 : } else if number.0 > count.0 - 1 {
158 3 : Err(ShardConfigError::InvalidNumber)
159 13365 : } else if stripe_size.0 == 0 {
160 1 : Err(ShardConfigError::InvalidStripeSize)
161 : } else {
162 13364 : Ok(Self {
163 13364 : number,
164 13364 : count,
165 13364 : layout: LAYOUT_V1,
166 13364 : stripe_size,
167 13364 : })
168 : }
169 13369 : }
170 :
171 : /// For use when creating ShardIdentity instances for new shards, where a creation request
172 : /// specifies the ShardParameters that apply to all shards.
173 464 : pub fn from_params(number: ShardNumber, params: &ShardParameters) -> Self {
174 464 : Self {
175 464 : number,
176 464 : count: params.count,
177 464 : layout: LAYOUT_V1,
178 464 : stripe_size: params.stripe_size,
179 464 : }
180 464 : }
181 :
182 12879749 : fn is_broken(&self) -> bool {
183 12879749 : self.layout == LAYOUT_BROKEN
184 12879749 : }
185 :
186 6157 : pub fn get_shard_number(&self, key: &Key) -> ShardNumber {
187 6157 : assert!(!self.is_broken());
188 6157 : key_to_shard_number(self.count, self.stripe_size, key)
189 6157 : }
190 :
191 : /// Return true if the key is stored only on this shard. This does not include
192 : /// global keys, see is_key_global().
193 : ///
194 : /// Shards must ingest _at least_ keys which return true from this check.
195 12873592 : pub fn is_key_local(&self, key: &Key) -> bool {
196 12873592 : assert!(!self.is_broken());
197 12873592 : if self.count < ShardCount(2) || (key_is_shard0(key) && self.number == ShardNumber(0)) {
198 10774960 : true
199 : } else {
200 2098632 : key_to_shard_number(self.count, self.stripe_size, key) == self.number
201 : }
202 12873592 : }
203 :
204 : /// Return true if the key should be stored on all shards, not just one.
205 2098633 : pub fn is_key_global(&self, key: &Key) -> bool {
206 2098633 : if key.is_slru_block_key()
207 2098633 : || key.is_slru_segment_size_key()
208 2098633 : || key.is_aux_file_key()
209 2098633 : || key.is_slru_dir_key()
210 : {
211 : // Special keys that are only stored on shard 0
212 0 : false
213 2098633 : } else if key.is_rel_block_key() {
214 : // Ordinary relation blocks are distributed across shards
215 2098628 : false
216 5 : } else if key.is_rel_size_key() {
217 : // All shards maintain rel size keys (although only shard 0 is responsible for
218 : // keeping it strictly accurate, other shards just reflect the highest block they've ingested)
219 5 : true
220 : } else {
221 : // For everything else, we assume it must be kept everywhere, because ingest code
222 : // might assume this -- this covers functionality where the ingest code has
223 : // not (yet) been made fully shard aware.
224 0 : true
225 : }
226 2098633 : }
227 :
228 : /// Return true if the key should be discarded if found in this shard's
229 : /// data store, e.g. during compaction after a split.
230 : ///
231 : /// Shards _may_ drop keys which return false here, but are not obliged to.
232 7491923 : pub fn is_key_disposable(&self, key: &Key) -> bool {
233 7491923 : if self.count < ShardCount(2) {
234 : // Fast path: unsharded tenant doesn't dispose of anything
235 5393290 : return false;
236 2098633 : }
237 2098633 :
238 2098633 : if self.is_key_global(key) {
239 5 : false
240 : } else {
241 2098628 : !self.is_key_local(key)
242 : }
243 7491923 : }
244 :
245 : /// Obtains the shard number and count combined into a `ShardIndex`.
246 618 : pub fn shard_index(&self) -> ShardIndex {
247 618 : ShardIndex {
248 618 : shard_count: self.count,
249 618 : shard_number: self.number,
250 618 : }
251 618 : }
252 :
253 16 : pub fn shard_slug(&self) -> String {
254 16 : if self.count > ShardCount(0) {
255 16 : format!("-{:02x}{:02x}", self.number.0, self.count.0)
256 : } else {
257 0 : String::new()
258 : }
259 16 : }
260 :
261 : /// Convenience for checking if this identity is the 0th shard in a tenant,
262 : /// for special cases on shard 0 such as ingesting relation sizes.
263 1504 : pub fn is_shard_zero(&self) -> bool {
264 1504 : self.number == ShardNumber(0)
265 1504 : }
266 : }
267 :
268 : /// Whether this key is always held on shard 0 (e.g. shard 0 holds all SLRU keys
269 : /// in order to be able to serve basebackup requests without peer communication).
270 4197301 : fn key_is_shard0(key: &Key) -> bool {
271 4197301 : // To decide what to shard out to shards >0, we apply a simple rule that only
272 4197301 : // relation pages are distributed to shards other than shard zero. Everything else gets
273 4197301 : // stored on shard 0. This guarantees that shard 0 can independently serve basebackup
274 4197301 : // requests, and any request other than those for particular blocks in relations.
275 4197301 : //
276 4197301 : // The only exception to this rule is "initfork" data -- this relates to postgres's UNLOGGED table
277 4197301 : // type. These are special relations, usually with only 0 or 1 blocks, and we store them on shard 0
278 4197301 : // because they must be included in basebackups.
279 4197301 : let is_initfork = key.field5 == INIT_FORKNUM;
280 4197301 :
281 4197301 : !key.is_rel_block_key() || is_initfork
282 4197301 : }
283 :
284 : /// Provide the same result as the function in postgres `hashfn.h` with the same name
285 4197339 : fn murmurhash32(mut h: u32) -> u32 {
286 4197339 : h ^= h >> 16;
287 4197339 : h = h.wrapping_mul(0x85ebca6b);
288 4197339 : h ^= h >> 13;
289 4197339 : h = h.wrapping_mul(0xc2b2ae35);
290 4197339 : h ^= h >> 16;
291 4197339 : h
292 4197339 : }
293 :
294 : /// Provide the same result as the function in postgres `hashfn.h` with the same name
295 2098670 : fn hash_combine(mut a: u32, mut b: u32) -> u32 {
296 2098670 : b = b.wrapping_add(0x9e3779b9);
297 2098670 : b = b.wrapping_add(a << 6);
298 2098670 : b = b.wrapping_add(a >> 2);
299 2098670 :
300 2098670 : a ^= b;
301 2098670 : a
302 2098670 : }
303 :
304 : /// Where a Key is to be distributed across shards, select the shard. This function
305 : /// does not account for keys that should be broadcast across shards.
306 : ///
307 : /// The hashing in this function must exactly match what we do in postgres smgr
308 : /// code. The resulting distribution of pages is intended to preserve locality within
309 : /// `stripe_size` ranges of contiguous block numbers in the same relation, while otherwise
310 : /// distributing data pseudo-randomly.
311 : ///
312 : /// The mapping of key to shard is not stable across changes to ShardCount: this is intentional
313 : /// and will be handled at higher levels when shards are split.
314 2104790 : fn key_to_shard_number(count: ShardCount, stripe_size: ShardStripeSize, key: &Key) -> ShardNumber {
315 2104790 : // Fast path for un-sharded tenants or broadcast keys
316 2104790 : if count < ShardCount(2) || key_is_shard0(key) {
317 6121 : return ShardNumber(0);
318 2098669 : }
319 2098669 :
320 2098669 : // relNode
321 2098669 : let mut hash = murmurhash32(key.field4);
322 2098669 : // blockNum/stripe size
323 2098669 : hash = hash_combine(hash, murmurhash32(key.field6 / stripe_size.0));
324 2098669 :
325 2098669 : ShardNumber((hash % count.0 as u32) as u8)
326 2104790 : }
327 :
328 : /// For debugging, while not exposing the internals.
329 : #[derive(Debug)]
330 : #[allow(unused)] // used by debug formatting by pagectl
331 : struct KeyShardingInfo {
332 : shard0: bool,
333 : shard_number: ShardNumber,
334 : }
335 :
336 0 : pub fn describe(
337 0 : key: &Key,
338 0 : shard_count: ShardCount,
339 0 : stripe_size: ShardStripeSize,
340 0 : ) -> impl std::fmt::Debug {
341 0 : KeyShardingInfo {
342 0 : shard0: key_is_shard0(key),
343 0 : shard_number: key_to_shard_number(shard_count, stripe_size, key),
344 0 : }
345 0 : }
346 :
347 : #[cfg(test)]
348 : mod tests {
349 : use std::str::FromStr;
350 :
351 : use utils::Hex;
352 : use utils::id::TenantId;
353 :
354 : use super::*;
355 :
356 : const EXAMPLE_TENANT_ID: &str = "1f359dd625e519a1a4e8d7509690f6fc";
357 :
358 : #[test]
359 1 : fn tenant_shard_id_string() -> Result<(), hex::FromHexError> {
360 1 : let example = TenantShardId {
361 1 : tenant_id: TenantId::from_str(EXAMPLE_TENANT_ID).unwrap(),
362 1 : shard_count: ShardCount(10),
363 1 : shard_number: ShardNumber(7),
364 1 : };
365 1 :
366 1 : let encoded = format!("{example}");
367 1 :
368 1 : let expected = format!("{EXAMPLE_TENANT_ID}-070a");
369 1 : assert_eq!(&encoded, &expected);
370 :
371 1 : let decoded = TenantShardId::from_str(&encoded)?;
372 :
373 1 : assert_eq!(example, decoded);
374 :
375 1 : Ok(())
376 1 : }
377 :
378 : #[test]
379 1 : fn tenant_shard_id_binary() -> Result<(), hex::FromHexError> {
380 1 : let example = TenantShardId {
381 1 : tenant_id: TenantId::from_str(EXAMPLE_TENANT_ID).unwrap(),
382 1 : shard_count: ShardCount(10),
383 1 : shard_number: ShardNumber(7),
384 1 : };
385 1 :
386 1 : let encoded = bincode::serialize(&example).unwrap();
387 1 : let expected: [u8; 18] = [
388 1 : 0x1f, 0x35, 0x9d, 0xd6, 0x25, 0xe5, 0x19, 0xa1, 0xa4, 0xe8, 0xd7, 0x50, 0x96, 0x90,
389 1 : 0xf6, 0xfc, 0x07, 0x0a,
390 1 : ];
391 1 : assert_eq!(Hex(&encoded), Hex(&expected));
392 :
393 1 : let decoded = bincode::deserialize(&encoded).unwrap();
394 1 :
395 1 : assert_eq!(example, decoded);
396 :
397 1 : Ok(())
398 1 : }
399 :
400 : #[test]
401 1 : fn tenant_shard_id_backward_compat() -> Result<(), hex::FromHexError> {
402 1 : // Test that TenantShardId can decode a TenantId in human
403 1 : // readable form
404 1 : let example = TenantId::from_str(EXAMPLE_TENANT_ID).unwrap();
405 1 : let encoded = format!("{example}");
406 1 :
407 1 : assert_eq!(&encoded, EXAMPLE_TENANT_ID);
408 :
409 1 : let decoded = TenantShardId::from_str(&encoded)?;
410 :
411 1 : assert_eq!(example, decoded.tenant_id);
412 1 : assert_eq!(decoded.shard_count, ShardCount(0));
413 1 : assert_eq!(decoded.shard_number, ShardNumber(0));
414 :
415 1 : Ok(())
416 1 : }
417 :
418 : #[test]
419 1 : fn tenant_shard_id_forward_compat() -> Result<(), hex::FromHexError> {
420 1 : // Test that a legacy TenantShardId encodes into a form that
421 1 : // can be decoded as TenantId
422 1 : let example_tenant_id = TenantId::from_str(EXAMPLE_TENANT_ID).unwrap();
423 1 : let example = TenantShardId::unsharded(example_tenant_id);
424 1 : let encoded = format!("{example}");
425 1 :
426 1 : assert_eq!(&encoded, EXAMPLE_TENANT_ID);
427 :
428 1 : let decoded = TenantId::from_str(&encoded)?;
429 :
430 1 : assert_eq!(example_tenant_id, decoded);
431 :
432 1 : Ok(())
433 1 : }
434 :
435 : #[test]
436 1 : fn tenant_shard_id_legacy_binary() -> Result<(), hex::FromHexError> {
437 1 : // Unlike in human readable encoding, binary encoding does not
438 1 : // do any special handling of legacy unsharded TenantIds: this test
439 1 : // is equivalent to the main test for binary encoding, just verifying
440 1 : // that the same behavior applies when we have used `unsharded()` to
441 1 : // construct a TenantShardId.
442 1 : let example = TenantShardId::unsharded(TenantId::from_str(EXAMPLE_TENANT_ID).unwrap());
443 1 : let encoded = bincode::serialize(&example).unwrap();
444 1 :
445 1 : let expected: [u8; 18] = [
446 1 : 0x1f, 0x35, 0x9d, 0xd6, 0x25, 0xe5, 0x19, 0xa1, 0xa4, 0xe8, 0xd7, 0x50, 0x96, 0x90,
447 1 : 0xf6, 0xfc, 0x00, 0x00,
448 1 : ];
449 1 : assert_eq!(Hex(&encoded), Hex(&expected));
450 :
451 1 : let decoded = bincode::deserialize::<TenantShardId>(&encoded).unwrap();
452 1 : assert_eq!(example, decoded);
453 :
454 1 : Ok(())
455 1 : }
456 :
457 : #[test]
458 1 : fn shard_identity_validation() -> Result<(), ShardConfigError> {
459 1 : // Happy cases
460 1 : ShardIdentity::new(ShardNumber(0), ShardCount(1), DEFAULT_STRIPE_SIZE)?;
461 1 : ShardIdentity::new(ShardNumber(0), ShardCount(1), ShardStripeSize(1))?;
462 1 : ShardIdentity::new(ShardNumber(254), ShardCount(255), ShardStripeSize(1))?;
463 :
464 1 : assert_eq!(
465 1 : ShardIdentity::new(ShardNumber(0), ShardCount(0), DEFAULT_STRIPE_SIZE),
466 1 : Err(ShardConfigError::InvalidCount)
467 1 : );
468 1 : assert_eq!(
469 1 : ShardIdentity::new(ShardNumber(10), ShardCount(10), DEFAULT_STRIPE_SIZE),
470 1 : Err(ShardConfigError::InvalidNumber)
471 1 : );
472 1 : assert_eq!(
473 1 : ShardIdentity::new(ShardNumber(11), ShardCount(10), DEFAULT_STRIPE_SIZE),
474 1 : Err(ShardConfigError::InvalidNumber)
475 1 : );
476 1 : assert_eq!(
477 1 : ShardIdentity::new(ShardNumber(255), ShardCount(255), DEFAULT_STRIPE_SIZE),
478 1 : Err(ShardConfigError::InvalidNumber)
479 1 : );
480 1 : assert_eq!(
481 1 : ShardIdentity::new(ShardNumber(0), ShardCount(1), ShardStripeSize(0)),
482 1 : Err(ShardConfigError::InvalidStripeSize)
483 1 : );
484 :
485 1 : Ok(())
486 1 : }
487 :
488 : #[test]
489 1 : fn shard_index_human_encoding() -> Result<(), hex::FromHexError> {
490 1 : let example = ShardIndex {
491 1 : shard_number: ShardNumber(13),
492 1 : shard_count: ShardCount(17),
493 1 : };
494 1 : let expected: String = "0d11".to_string();
495 1 : let encoded = format!("{example}");
496 1 : assert_eq!(&encoded, &expected);
497 :
498 1 : let decoded = ShardIndex::from_str(&encoded)?;
499 1 : assert_eq!(example, decoded);
500 1 : Ok(())
501 1 : }
502 :
503 : #[test]
504 1 : fn shard_index_binary_encoding() -> Result<(), hex::FromHexError> {
505 1 : let example = ShardIndex {
506 1 : shard_number: ShardNumber(13),
507 1 : shard_count: ShardCount(17),
508 1 : };
509 1 : let expected: [u8; 2] = [0x0d, 0x11];
510 1 :
511 1 : let encoded = bincode::serialize(&example).unwrap();
512 1 : assert_eq!(Hex(&encoded), Hex(&expected));
513 1 : let decoded = bincode::deserialize(&encoded).unwrap();
514 1 : assert_eq!(example, decoded);
515 :
516 1 : Ok(())
517 1 : }
518 :
519 : // These are only smoke tests to spot check that our implementation doesn't
520 : // deviate from a few examples values: not aiming to validate the overall
521 : // hashing algorithm.
522 : #[test]
523 1 : fn murmur_hash() {
524 1 : assert_eq!(murmurhash32(0), 0);
525 :
526 1 : assert_eq!(hash_combine(0xb1ff3b40, 0), 0xfb7923c9);
527 1 : }
528 :
529 : #[test]
530 1 : fn shard_mapping() {
531 1 : let key = Key {
532 1 : field1: 0x00,
533 1 : field2: 0x67f,
534 1 : field3: 0x5,
535 1 : field4: 0x400c,
536 1 : field5: 0x00,
537 1 : field6: 0x7d06,
538 1 : };
539 1 :
540 1 : let shard = key_to_shard_number(ShardCount(10), DEFAULT_STRIPE_SIZE, &key);
541 1 : assert_eq!(shard, ShardNumber(8));
542 1 : }
543 :
544 : #[test]
545 1 : fn shard_id_split() {
546 1 : let tenant_id = TenantId::generate();
547 1 : let parent = TenantShardId::unsharded(tenant_id);
548 1 :
549 1 : // Unsharded into 2
550 1 : assert_eq!(
551 1 : parent.split(ShardCount(2)),
552 1 : vec![
553 1 : TenantShardId {
554 1 : tenant_id,
555 1 : shard_count: ShardCount(2),
556 1 : shard_number: ShardNumber(0)
557 1 : },
558 1 : TenantShardId {
559 1 : tenant_id,
560 1 : shard_count: ShardCount(2),
561 1 : shard_number: ShardNumber(1)
562 1 : }
563 1 : ]
564 1 : );
565 :
566 : // Unsharded into 4
567 1 : assert_eq!(
568 1 : parent.split(ShardCount(4)),
569 1 : vec![
570 1 : TenantShardId {
571 1 : tenant_id,
572 1 : shard_count: ShardCount(4),
573 1 : shard_number: ShardNumber(0)
574 1 : },
575 1 : TenantShardId {
576 1 : tenant_id,
577 1 : shard_count: ShardCount(4),
578 1 : shard_number: ShardNumber(1)
579 1 : },
580 1 : TenantShardId {
581 1 : tenant_id,
582 1 : shard_count: ShardCount(4),
583 1 : shard_number: ShardNumber(2)
584 1 : },
585 1 : TenantShardId {
586 1 : tenant_id,
587 1 : shard_count: ShardCount(4),
588 1 : shard_number: ShardNumber(3)
589 1 : }
590 1 : ]
591 1 : );
592 :
593 : // count=1 into 2 (check this works the same as unsharded.)
594 1 : let parent = TenantShardId {
595 1 : tenant_id,
596 1 : shard_count: ShardCount(1),
597 1 : shard_number: ShardNumber(0),
598 1 : };
599 1 : assert_eq!(
600 1 : parent.split(ShardCount(2)),
601 1 : vec![
602 1 : TenantShardId {
603 1 : tenant_id,
604 1 : shard_count: ShardCount(2),
605 1 : shard_number: ShardNumber(0)
606 1 : },
607 1 : TenantShardId {
608 1 : tenant_id,
609 1 : shard_count: ShardCount(2),
610 1 : shard_number: ShardNumber(1)
611 1 : }
612 1 : ]
613 1 : );
614 :
615 : // count=2 into count=8
616 1 : let parent = TenantShardId {
617 1 : tenant_id,
618 1 : shard_count: ShardCount(2),
619 1 : shard_number: ShardNumber(1),
620 1 : };
621 1 : assert_eq!(
622 1 : parent.split(ShardCount(8)),
623 1 : vec![
624 1 : TenantShardId {
625 1 : tenant_id,
626 1 : shard_count: ShardCount(8),
627 1 : shard_number: ShardNumber(1)
628 1 : },
629 1 : TenantShardId {
630 1 : tenant_id,
631 1 : shard_count: ShardCount(8),
632 1 : shard_number: ShardNumber(3)
633 1 : },
634 1 : TenantShardId {
635 1 : tenant_id,
636 1 : shard_count: ShardCount(8),
637 1 : shard_number: ShardNumber(5)
638 1 : },
639 1 : TenantShardId {
640 1 : tenant_id,
641 1 : shard_count: ShardCount(8),
642 1 : shard_number: ShardNumber(7)
643 1 : },
644 1 : ]
645 1 : );
646 1 : }
647 : }
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