From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 11 Jul 2018 19:33:07 +0300 From: Vladimir Davydov Subject: Re: [RFC PATCH 04/23] vinyl: make point lookup always return the latest tuple version Message-ID: <20180711163307.vxwzle6claiazwrg@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180710164343.xgxdwk4ovbhdmmbo@esperanza> References: <20180710161926.GC22105@chai> <20180710164343.xgxdwk4ovbhdmmbo@esperanza> To: Konstantin Osipov Cc: tarantool-patches@freelists.org List-ID: BTW this patch makes the behavior of vy_point_lookup() consistent with vy_read_iterator: both iterators now return the newest tuple version. Also, it allows to simplify vy_squash_process() - see the patch below (I pushed it on the branch, you may want to cherry-pick it as well): >From c001e3f1a320bb804f49ca19ec540fee094dacc3 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Wed, 11 Jul 2018 19:14:24 +0300 Subject: [PATCH] vinyl: simplify vy_squash_process Since vy_point_lookup() now guarantees that it returns the newest tuple version, we can remove the code that squashes UPSERTs from vy_squash_process(). diff --git a/src/box/vinyl.c b/src/box/vinyl.c index a9603560..2d1a6fc0 100644 --- a/src/box/vinyl.c +++ b/src/box/vinyl.c @@ -3585,11 +3585,6 @@ vy_squash_process(struct vy_squash *squash) struct vy_lsm *lsm = squash->lsm; struct vy_env *env = squash->env; - /* - * vy_apply_upsert() is used for primary key only, - * so this is the same as lsm->key_def - */ - struct key_def *def = lsm->cmp_def; /* Upserts enabled only in the primary index LSM tree. */ assert(lsm->index_id == 0); @@ -3607,8 +3602,10 @@ vy_squash_process(struct vy_squash *squash) /* * While we were reading on-disk runs, new statements could - * have been inserted into the in-memory tree. Apply them to - * the result. + * have been prepared for the squashed key. We mustn't apply + * them, because they may be rolled back, but we must adjust + * their n_upserts counter so that they will get squashed by + * vy_lsm_commit_upsert(). */ struct vy_mem *mem = lsm->mem; struct tree_mem_key tree_key = { @@ -3625,108 +3622,20 @@ vy_squash_process(struct vy_squash *squash) tuple_unref(result); return 0; } - /** - * Algorithm of the squashing. - * Assume, during building the non-UPSERT statement - * 'result' in the mem some new UPSERTs were inserted, and - * some of them were commited, while the other were just - * prepared. And lets UPSERT_THRESHOLD to be equal to 3, - * for example. - * Mem - * -------------------------------------+ - * UPSERT, lsn = 1, n_ups = 0 | - * UPSERT, lsn = 2, n_ups = 1 | Commited - * UPSERT, lsn = 3, n_ups = 2 | - * -------------------------------------+ - * UPSERT, lsn = MAX, n_ups = 3 | - * UPSERT, lsn = MAX + 1, n_ups = 4 | Prepared - * UPSERT, lsn = MAX + 2, n_ups = 5 | - * -------------------------------------+ - * In such a case the UPSERT statements with - * lsns = {1, 2, 3} are squashed. But now the n_upsert - * values in the prepared statements are not correct. - * If we will not update values, then the - * vy_lsm_commit_upsert will not be able to squash them. - * - * So after squashing it is necessary to update n_upsert - * value in the prepared statements: - * Mem - * -------------------------------------+ - * UPSERT, lsn = 1, n_ups = 0 | - * UPSERT, lsn = 2, n_ups = 1 | Commited - * REPLACE, lsn = 3 | - * -------------------------------------+ - * UPSERT, lsn = MAX, n_ups = 0 !!! | - * UPSERT, lsn = MAX + 1, n_ups = 1 !!! | Prepared - * UPSERT, lsn = MAX + 2, n_ups = 2 !!! | - * -------------------------------------+ - */ vy_mem_tree_iterator_prev(&mem->tree, &mem_itr); - const struct tuple *mem_stmt; - int64_t stmt_lsn; - /* - * According to the described algorithm, squash the - * commited UPSERTs at first. - */ + uint8_t n_upserts = 0; while (!vy_mem_tree_iterator_is_invalid(&mem_itr)) { + const struct tuple *mem_stmt; mem_stmt = *vy_mem_tree_iterator_get_elem(&mem->tree, &mem_itr); - stmt_lsn = vy_stmt_lsn(mem_stmt); - if (vy_tuple_compare(result, mem_stmt, def) != 0) - break; - /** - * Leave alone prepared statements; they will be handled - * in vy_range_commit_stmt. - */ - if (stmt_lsn >= MAX_LSN) + if (vy_tuple_compare(result, mem_stmt, lsm->cmp_def) != 0 || + vy_stmt_type(mem_stmt) != IPROTO_UPSERT) break; - if (vy_stmt_type(mem_stmt) != IPROTO_UPSERT) { - /** - * Somebody inserted non-upsert statement, - * squashing is useless. - */ - tuple_unref(result); - return 0; - } - assert(lsm->index_id == 0); - struct tuple *applied = vy_apply_upsert(mem_stmt, result, def, - mem->format, true); - lsm->stat.upsert.applied++; - tuple_unref(result); - if (applied == NULL) - return -1; - result = applied; - /** - * In normal cases we get a result with the same lsn as - * in mem_stmt. - * But if there are buggy upserts that do wrong things, - * they are ignored and the result has lower lsn. - * We should fix the lsn in any case to replace - * exactly mem_stmt in general and the buggy upsert - * in particular. - */ - vy_stmt_set_lsn(result, stmt_lsn); + assert(vy_stmt_lsn(mem_stmt) >= MAX_LSN); + vy_stmt_set_n_upserts((struct tuple *)mem_stmt, n_upserts); + if (n_upserts <= VY_UPSERT_THRESHOLD) + ++n_upserts; vy_mem_tree_iterator_prev(&mem->tree, &mem_itr); } - /* - * The second step of the algorithm above is updating of - * n_upsert values of the prepared UPSERTs. - */ - if (stmt_lsn >= MAX_LSN) { - uint8_t n_upserts = 0; - while (!vy_mem_tree_iterator_is_invalid(&mem_itr)) { - mem_stmt = *vy_mem_tree_iterator_get_elem(&mem->tree, - &mem_itr); - if (vy_tuple_compare(result, mem_stmt, def) != 0 || - vy_stmt_type(mem_stmt) != IPROTO_UPSERT) - break; - assert(vy_stmt_lsn(mem_stmt) >= MAX_LSN); - vy_stmt_set_n_upserts((struct tuple *)mem_stmt, - n_upserts); - if (n_upserts <= VY_UPSERT_THRESHOLD) - ++n_upserts; - vy_mem_tree_iterator_prev(&mem->tree, &mem_itr); - } - } lsm->stat.upsert.squashed++;