path: root/storage/tokudb/tokudb_card.h

/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
#ident "$Id$"
/*
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  This program is free software; you can redistribute it and/or modify
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  following conditions are met:

      * Redistributions of source code must retain this COPYING
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COPYRIGHT NOTICE:

  TokuDB, Tokutek Fractal Tree Indexing Library.
  Copyright (C) 2007-2013 Tokutek, Inc.

DISCLAIMER:

  This program is distributed in the hope that it will be useful, but
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  General Public License for more details.

UNIVERSITY PATENT NOTICE:

  The technology is licensed by the Massachusetts Institute of
  Technology, Rutgers State University of New Jersey, and the Research
  Foundation of State University of New York at Stony Brook under
  United States of America Serial No. 11/760379 and to the patents
  and/or patent applications resulting from it.

PATENT MARKING NOTICE:

  This software is covered by US Patent No. 8,185,551.
  This software is covered by US Patent No. 8,489,638.

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*/

#ident "Copyright (c) 2007-2013 Tokutek Inc.  All rights reserved."
#ident "The technology is licensed by the Massachusetts Institute of Technology, Rutgers State University of New Jersey, and the Research Foundation of State University of New York at Stony Brook under United States of America Serial No. 11/760379 and to the patents and/or patent applications resulting from it."
namespace tokudb {
    uint compute_total_key_parts(TABLE_SHARE *table_share) {
        uint total_key_parts = 0;
        for (uint i = 0; i < table_share->keys; i++) {
            total_key_parts += get_key_parts(&table_share->key_info[i]);
        }
        return total_key_parts;
    }

    // Set the key_info cardinality counters for the table.
    void set_card_in_key_info(TABLE *table, uint rec_per_keys, uint64_t rec_per_key[]) {
        uint next_key_part = 0;
        for (uint i = 0; i < table->s->keys; i++) {
            bool is_unique_key = (i == table->s->primary_key) || (table->key_info[i].flags & HA_NOSAME);
            uint num_key_parts = get_key_parts(&table->key_info[i]);
            for (uint j = 0; j < num_key_parts; j++) {
                assert(next_key_part < rec_per_keys);
                ulong val = rec_per_key[next_key_part++];
                if (is_unique_key && j == num_key_parts-1)
                    val = 1;
                table->key_info[i].rec_per_key[j] = val;
            }
        }
    }
    
    // Put the cardinality counters into the status dictionary.
    void set_card_in_status(DB *status_db, DB_TXN *txn, uint rec_per_keys, uint64_t rec_per_key[]) {
        // encode cardinality into the buffer
        tokudb::buffer b;
        size_t s;
        s = b.append_ui<uint32_t>(rec_per_keys);
        assert(s > 0);
        for (uint i = 0; i < rec_per_keys; i++) {
            s = b.append_ui<uint64_t>(rec_per_key[i]);
            assert(s > 0);
        }
        // write cardinality to status
        int error = write_to_status(status_db, hatoku_cardinality, b.data(), b.size(), txn);
        assert(error == 0);
    }

    // Get the cardinality counters from the status dictionary.
    int get_card_from_status(DB *status_db, DB_TXN *txn, uint rec_per_keys, uint64_t rec_per_key[]) {
        // read cardinality from status
        void *buf = 0; size_t buf_size = 0;
        int error = get_status_realloc(status_db, txn, hatoku_cardinality, &buf, &buf_size);
        if (error == 0) {
            // decode cardinality from the buffer
            tokudb::buffer b(buf, 0, buf_size);
            size_t s;
            uint32_t num_parts;
            s = b.consume_ui<uint32_t>(&num_parts);
            if (s == 0 || num_parts != rec_per_keys) 
                error = EINVAL;
            if (error == 0) {
                for (uint i = 0; i < rec_per_keys; i++) {
                    s = b.consume_ui<uint64_t>(&rec_per_key[i]);
                    if (s == 0) {
                        error = EINVAL;
                        break;
                    }
                }
            }
        }
        // cleanup
        free(buf);
        return error;
    }

    // Delete the cardinality counters from the status dictionary.
    void delete_card_from_status(DB *status_db, DB_TXN *txn) {
        int error = remove_from_status(status_db, hatoku_cardinality, txn);
        assert(error == 0);
    }

    bool find_index_of_key(const char *key_name, TABLE_SHARE *table_share, uint *index_offset_ptr) {
        for (uint i = 0; i < table_share->keys; i++) {
            if (strcmp(key_name, table_share->key_info[i].name) == 0) {
                *index_offset_ptr = i;
                return true;
            }
        }
        return false;
    }

    // Altered table cardinality = select cardinality data from current table cardinality for keys that exist 
    // in the altered table and the current table.
    void set_card_from_status(DB *status_db, DB_TXN *txn, TABLE_SHARE *table_share, TABLE_SHARE *altered_table_share) {
        int error;
        // read existing cardinality data from status
        uint table_total_key_parts = tokudb::compute_total_key_parts(table_share);
        uint64_t rec_per_key[table_total_key_parts];
        error = get_card_from_status(status_db, txn, table_total_key_parts, rec_per_key);
        // set altered records per key to unknown
        uint altered_table_total_key_parts = tokudb::compute_total_key_parts(altered_table_share);
        uint64_t altered_rec_per_key[altered_table_total_key_parts];
        for (uint i = 0; i < altered_table_total_key_parts; i++)
            altered_rec_per_key[i] = 0;
        // compute the beginning of the key offsets in the original table
        uint orig_key_offset[table_share->keys];
        uint orig_key_parts = 0;
        for (uint i = 0; i < table_share->keys; i++) {
            orig_key_offset[i] = orig_key_parts;
            orig_key_parts += get_key_parts(&table_share->key_info[i]);
        }
        // if orig card data exists, then use it to compute new card data
        if (error == 0) {
            uint next_key_parts = 0;
            for (uint i = 0; error == 0 && i < altered_table_share->keys; i++) {
                uint ith_key_parts = get_key_parts(&altered_table_share->key_info[i]);
                uint orig_key_index;
                if (find_index_of_key(altered_table_share->key_info[i].name, table_share, &orig_key_index)) {
                    memcpy(&altered_rec_per_key[next_key_parts], &rec_per_key[orig_key_offset[orig_key_index]], ith_key_parts);
                }
                next_key_parts += ith_key_parts;
            }
        }
        if (error == 0)
            set_card_in_status(status_db, txn, altered_table_total_key_parts, altered_rec_per_key);
        else
            delete_card_from_status(status_db, txn);
    }

    // Compute records per key for all key parts of the ith key of the table.
    // For each key part, put records per key part in *rec_per_key_part[key_part_index].
    // Returns 0 if success, otherwise an error number.
    // TODO statistical dives into the FT
    int analyze_card(DB *db, DB_TXN *txn, bool is_unique __attribute__((unused)), uint64_t num_key_parts, uint64_t *rec_per_key_part,
                     int (*key_compare)(DB *, const DBT *, const DBT *, uint),
                     int (*analyze_progress)(void *extra, uint64_t rows), void *progress_extra) {
        int error = 0;
        uint64_t rows = 0;
        uint64_t unique_rows[num_key_parts];
        if (is_unique && num_key_parts == 1) {
            // dont compute for unique keys with a single part.  we already know the answer.
            rows = unique_rows[0] = 1;
        } else {
            DBC *cursor = NULL;
            error = db->cursor(db, txn, &cursor, 0);
            if (error == 0) {
                for (uint64_t i = 0; i < num_key_parts; i++)
                    unique_rows[i] = 1;
                // stop looking when the entire dictionary was analyzed, or a cap on execution time was reached, or the analyze was killed.
                DBT key = {}; key.flags = DB_DBT_REALLOC;
                DBT prev_key = {}; prev_key.flags = DB_DBT_REALLOC;
                while (1) {
                    error = cursor->c_get(cursor, &key, 0, DB_NEXT);
                    if (error != 0) {
                        if (error == DB_NOTFOUND)
                        error = 0; // eof is not an error
                        break;
                    }
                    rows++;
                    // first row is a unique row, otherwise compare with the previous key
                    bool copy_key = false;
                    if (rows == 1) {
                        copy_key = true;
                    } else {
                        // compare this key with the previous key.  ignore appended PK for SK's.
                        // TODO if a prefix is different, then all larger keys that include the prefix are also different.
                        // TODO if we are comparing the entire primary key or the entire unique secondary key, then the cardinality must be 1,
                        // so we can avoid computing it.
                        for (uint64_t i = 0; i < num_key_parts; i++) {
                            int cmp = key_compare(db, &prev_key, &key, i+1);
                            if (cmp != 0) {
                                unique_rows[i]++;
                                copy_key = true;
                            }
                        }
                    }
                    // prev_key = key
                    if (copy_key) {
                        prev_key.data = realloc(prev_key.data, key.size);
                        assert(prev_key.data);
                        prev_key.size = key.size;
                        memcpy(prev_key.data, key.data, prev_key.size);
                    }
                    // check for limit
                    if (analyze_progress && (rows % 1000) == 0) {
                        error = analyze_progress(progress_extra, rows);
                        if (error)
                            break;
                    }
                }
                // cleanup
                free(key.data);
                free(prev_key.data);
                int close_error = cursor->c_close(cursor);
                assert(close_error == 0);
            }
        }
        // return cardinality
        if (error == 0 || error == ETIME) {
            for (uint64_t i = 0; i < num_key_parts; i++)
                rec_per_key_part[i]  = rows / unique_rows[i];
        }
        return error;
    }
}