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whitepaper: re-add 10 missing entries + 11 new defects this session, count 578→590; rebuild PDF

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russell@unturf.com 2026-03-27 22:18:31 -04:00
parent e4ee168b1e
commit 2e4f7807d5
401 changed files with 3914 additions and 114 deletions
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84
defects/mysql/unit/MysqlTest.java
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@ -8,6 +8,7 @@ import java.util.*;
* mysql-0001: SHOW GRANTS USING roles — O(U*G) vector find vs O(U) hash lookup
* mysql-0002: has_global_grant fallback — O(P) multimap equal_range+find vs O(1) map lookup
* mysql-0003: setup_fields() iterator recovery — O(F²) std::find vs O(F) index loop
* mysql-0004: dict_index_find_and_set_cols() col_added — O(F²) std::find vs O(F) unordered_set
*
* No JUnit. Prints N/N PASS.
*/
@ -199,6 +200,66 @@ public class MysqlTest {
return ops;
}
// -----------------------------------------------------------------------
// mysql-0004 — dict_index_find_and_set_cols: O(F²) col_added vector dedup
//
// Models storage/innobase/dict/dict0dict.cc:dict_index_find_and_set_cols():
// std::vector<ulint> col_added;
// for (ulint i = 0; i < index->n_fields; i++) {
// for (j = 0; j < table->n_cols; j++) {
// if name matches {
// bool exists = std::find(col_added.begin(), col_added.end(), j)
// != col_added.end(); // O(|col_added|) = O(i)
// if exists: goto dup_err;
// col_added.push_back(j); // col_added grows
// }
// }
// }
//
// F index fields: 0+1+...+(F-1) = O(F²) total comparison ops.
// Fix: std::unordered_set<ulint> → O(1) per lookup → O(F) total.
// -----------------------------------------------------------------------
/**
* Simulate dict_index_find_and_set_cols with O(F²) std::find duplicate check.
* F = number of index fields (all distinct columns, no duplicates).
* Returns total comparison operations.
*/
static long dictIndexColAddedSlow(int F) {
List<Integer> colAdded = new ArrayList<>(F);
long ops = 0;
for (int i = 0; i < F; i++) {
int colIdx = i; // each field maps to a distinct column
// std::find: O(|col_added|) scan
boolean exists = false;
for (Integer c : colAdded) {
ops++;
if (c.equals(colIdx)) { exists = true; break; }
}
if (!exists) {
colAdded.add(colIdx);
}
}
return ops;
}
/**
* Fixed version: unordered_set for O(1) duplicate detection.
* Models replacing std::vector + std::find with std::unordered_set.
*/
static long dictIndexColAddedFast(int F) {
Set<Integer> colAdded = new HashSet<>(F * 2);
long ops = 0;
for (int i = 0; i < F; i++) {
int colIdx = i;
ops++; // O(1) hash lookup
if (!colAdded.contains(colIdx)) {
colAdded.add(colIdx);
}
}
return ops;
}
// -----------------------------------------------------------------------
// Main
// -----------------------------------------------------------------------
@ -272,6 +333,29 @@ public class MysqlTest {
if (!pass) { System.out.printf(" FAIL mysql-0003: slowOps=%,d fastOps=%,d (expected >10x)%n", slowOps[0], fastOps[0]); failures++; }
}
// --- mysql-0004: dict_index_find_and_set_cols col_added O(F²) ---
{
int F = 200;
long[] slowOps = new long[1], fastOps = new long[1];
Runnable slow = () -> slowOps[0] = dictIndexColAddedSlow(F);
Runnable fast = () -> fastOps[0] = dictIndexColAddedFast(F);
slow.run(); fast.run();
long t0 = System.nanoTime(); slow.run(); long sMs = (System.nanoTime() - t0) / 1_000_000;
long t1 = System.nanoTime(); fast.run(); long fMs = (System.nanoTime() - t1) / 1_000_000;
double speedup = fastOps[0] > 0 ? (double) slowOps[0] / fastOps[0] : 0;
System.out.printf(" %-60s slow:%4dms (%,d ops) fast:%4dms (%,d ops) speedup:%.1fx%n",
"mysql-0004 dict_index_col_added O(F²) vs O(F)", sMs, slowOps[0], fMs, fastOps[0], speedup);
total++;
// At F=200: slow=0+1+...+199=19900 ops; fast=200 ops → ratio >50x
boolean pass = slowOps[0] > fastOps[0] * 50L;
if (!pass) { System.out.printf(" FAIL mysql-0004: slowOps=%,d fastOps=%,d (expected >50x)%n",
slowOps[0], fastOps[0]); failures++; }
else System.out.println(" PASS mysql-0004");
}
System.out.println("=".repeat(100));
System.out.printf("%d/%d %s%n", total - failures, total, failures == 0 ? "PASS" : "FAIL");
if (failures > 0) System.exit(1);